diff --git a/euler/.gitignore b/euler/.gitignore
new file mode 100644
index 00000000..ea8c4bf7
--- /dev/null
+++ b/euler/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/euler/Cargo.lock b/euler/Cargo.lock
new file mode 100644
index 00000000..7744ed5e
--- /dev/null
+++ b/euler/Cargo.lock
@@ -0,0 +1,15 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "euler-001"
+version = "0.1.0"
+
+[[package]]
+name = "euler-002"
+version = "0.1.0"
+
+[[package]]
+name = "euler-004"
+version = "0.1.0"
diff --git a/euler/Cargo.toml b/euler/Cargo.toml
new file mode 100644
index 00000000..41537c54
--- /dev/null
+++ b/euler/Cargo.toml
@@ -0,0 +1,10 @@
+[workspace]
+resolver = "2"
+
+members = [
+ "rust/euler-*",
+]
+
+exclude = [
+ "rust/deprecated",
+]
diff --git a/euler/LICENSE b/euler/LICENSE
new file mode 100644
index 00000000..d41c0bd9
--- /dev/null
+++ b/euler/LICENSE
@@ -0,0 +1,232 @@
+GNU GENERAL PUBLIC LICENSE
+Version 3, 29 June 2007
+
+Copyright © 2007 Free Software Foundation, Inc.
+
+Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
+
+Preamble
+
+The GNU General Public License is a free, copyleft license for software and other kinds of works.
+
+The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program--to make sure it remains free software for all its users. We, the Free Software Foundation, use the GNU General Public License for most of our software; it applies also to any other work released this way by its authors. You can apply it to your programs, too.
+
+When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for them if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs, and that you know you can do these things.
+
+To protect your rights, we need to prevent others from denying you these rights or asking you to surrender the rights. Therefore, you have certain responsibilities if you distribute copies of the software, or if you modify it: responsibilities to respect the freedom of others.
+
+For example, if you distribute copies of such a program, whether gratis or for a fee, you must pass on to the recipients the same freedoms that you received. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.
+
+Developers that use the GNU GPL protect your rights with two steps: (1) assert copyright on the software, and (2) offer you this License giving you legal permission to copy, distribute and/or modify it.
+
+For the developers' and authors' protection, the GPL clearly explains that there is no warranty for this free software. For both users' and authors' sake, the GPL requires that modified versions be marked as changed, so that their problems will not be attributed erroneously to authors of previous versions.
+
+Some devices are designed to deny users access to install or run modified versions of the software inside them, although the manufacturer can do so. This is fundamentally incompatible with the aim of protecting users' freedom to change the software. The systematic pattern of such abuse occurs in the area of products for individuals to use, which is precisely where it is most unacceptable. Therefore, we have designed this version of the GPL to prohibit the practice for those products. If such problems arise substantially in other domains, we stand ready to extend this provision to those domains in future versions of the GPL, as needed to protect the freedom of users.
+
+Finally, every program is threatened constantly by software patents. States should not allow patents to restrict development and use of software on general-purpose computers, but in those that do, we wish to avoid the special danger that patents applied to a free program could make it effectively proprietary. To prevent this, the GPL assures that patents cannot be used to render the program non-free.
+
+The precise terms and conditions for copying, distribution and modification follow.
+
+TERMS AND CONDITIONS
+
+0. Definitions.
+
+“This License” refers to version 3 of the GNU General Public License.
+
+“Copyright” also means copyright-like laws that apply to other kinds of works, such as semiconductor masks.
+
+“The Program” refers to any copyrightable work licensed under this License. Each licensee is addressed as “you”. “Licensees” and “recipients” may be individuals or organizations.
+
+To “modify” a work means to copy from or adapt all or part of the work in a fashion requiring copyright permission, other than the making of an exact copy. The resulting work is called a “modified version” of the earlier work or a work “based on” the earlier work.
+
+A “covered work” means either the unmodified Program or a work based on the Program.
+
+To “propagate” a work means to do anything with it that, without permission, would make you directly or secondarily liable for infringement under applicable copyright law, except executing it on a computer or modifying a private copy. Propagation includes copying, distribution (with or without modification), making available to the public, and in some countries other activities as well.
+
+To “convey” a work means any kind of propagation that enables other parties to make or receive copies. Mere interaction with a user through a computer network, with no transfer of a copy, is not conveying.
+
+An interactive user interface displays “Appropriate Legal Notices” to the extent that it includes a convenient and prominently visible feature that (1) displays an appropriate copyright notice, and (2) tells the user that there is no warranty for the work (except to the extent that warranties are provided), that licensees may convey the work under this License, and how to view a copy of this License. If the interface presents a list of user commands or options, such as a menu, a prominent item in the list meets this criterion.
+
+1. Source Code.
+The “source code” for a work means the preferred form of the work for making modifications to it. “Object code” means any non-source form of a work.
+
+A “Standard Interface” means an interface that either is an official standard defined by a recognized standards body, or, in the case of interfaces specified for a particular programming language, one that is widely used among developers working in that language.
+
+The “System Libraries” of an executable work include anything, other than the work as a whole, that (a) is included in the normal form of packaging a Major Component, but which is not part of that Major Component, and (b) serves only to enable use of the work with that Major Component, or to implement a Standard Interface for which an implementation is available to the public in source code form. A “Major Component”, in this context, means a major essential component (kernel, window system, and so on) of the specific operating system (if any) on which the executable work runs, or a compiler used to produce the work, or an object code interpreter used to run it.
+
+The “Corresponding Source” for a work in object code form means all the source code needed to generate, install, and (for an executable work) run the object code and to modify the work, including scripts to control those activities. However, it does not include the work's System Libraries, or general-purpose tools or generally available free programs which are used unmodified in performing those activities but which are not part of the work. For example, Corresponding Source includes interface definition files associated with source files for the work, and the source code for shared libraries and dynamically linked subprograms that the work is specifically designed to require, such as by intimate data communication or control flow between those subprograms and other parts of the work.
+
+The Corresponding Source need not include anything that users can regenerate automatically from other parts of the Corresponding Source.
+
+The Corresponding Source for a work in source code form is that same work.
+
+2. Basic Permissions.
+All rights granted under this License are granted for the term of copyright on the Program, and are irrevocable provided the stated conditions are met. This License explicitly affirms your unlimited permission to run the unmodified Program. The output from running a covered work is covered by this License only if the output, given its content, constitutes a covered work. This License acknowledges your rights of fair use or other equivalent, as provided by copyright law.
+
+You may make, run and propagate covered works that you do not convey, without conditions so long as your license otherwise remains in force. You may convey covered works to others for the sole purpose of having them make modifications exclusively for you, or provide you with facilities for running those works, provided that you comply with the terms of this License in conveying all material for which you do not control copyright. Those thus making or running the covered works for you must do so exclusively on your behalf, under your direction and control, on terms that prohibit them from making any copies of your copyrighted material outside their relationship with you.
+
+Conveying under any other circumstances is permitted solely under the conditions stated below. Sublicensing is not allowed; section 10 makes it unnecessary.
+
+3. Protecting Users' Legal Rights From Anti-Circumvention Law.
+No covered work shall be deemed part of an effective technological measure under any applicable law fulfilling obligations under article 11 of the WIPO copyright treaty adopted on 20 December 1996, or similar laws prohibiting or restricting circumvention of such measures.
+
+When you convey a covered work, you waive any legal power to forbid circumvention of technological measures to the extent such circumvention is effected by exercising rights under this License with respect to the covered work, and you disclaim any intention to limit operation or modification of the work as a means of enforcing, against the work's users, your or third parties' legal rights to forbid circumvention of technological measures.
+
+4. Conveying Verbatim Copies.
+You may convey verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice; keep intact all notices stating that this License and any non-permissive terms added in accord with section 7 apply to the code; keep intact all notices of the absence of any warranty; and give all recipients a copy of this License along with the Program.
+
+You may charge any price or no price for each copy that you convey, and you may offer support or warranty protection for a fee.
+
+5. Conveying Modified Source Versions.
+You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of section 4, provided that you also meet all of these conditions:
+
+ a) The work must carry prominent notices stating that you modified it, and giving a relevant date.
+
+ b) The work must carry prominent notices stating that it is released under this License and any conditions added under section 7. This requirement modifies the requirement in section 4 to “keep intact all notices”.
+
+ c) You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it.
+
+ d) If the work has interactive user interfaces, each must display Appropriate Legal Notices; however, if the Program has interactive interfaces that do not display Appropriate Legal Notices, your work need not make them do so.
+
+A compilation of a covered work with other separate and independent works, which are not by their nature extensions of the covered work, and which are not combined with it such as to form a larger program, in or on a volume of a storage or distribution medium, is called an “aggregate” if the compilation and its resulting copyright are not used to limit the access or legal rights of the compilation's users beyond what the individual works permit. Inclusion of a covered work in an aggregate does not cause this License to apply to the other parts of the aggregate.
+
+6. Conveying Non-Source Forms.
+You may convey a covered work in object code form under the terms of sections 4 and 5, provided that you also convey the machine-readable Corresponding Source under the terms of this License, in one of these ways:
+
+ a) Convey the object code in, or embodied in, a physical product (including a physical distribution medium), accompanied by the Corresponding Source fixed on a durable physical medium customarily used for software interchange.
+
+ b) Convey the object code in, or embodied in, a physical product (including a physical distribution medium), accompanied by a written offer, valid for at least three years and valid for as long as you offer spare parts or customer support for that product model, to give anyone who possesses the object code either (1) a copy of the Corresponding Source for all the software in the product that is covered by this License, on a durable physical medium customarily used for software interchange, for a price no more than your reasonable cost of physically performing this conveying of source, or (2) access to copy the Corresponding Source from a network server at no charge.
+
+ c) Convey individual copies of the object code with a copy of the written offer to provide the Corresponding Source. This alternative is allowed only occasionally and noncommercially, and only if you received the object code with such an offer, in accord with subsection 6b.
+
+ d) Convey the object code by offering access from a designated place (gratis or for a charge), and offer equivalent access to the Corresponding Source in the same way through the same place at no further charge. You need not require recipients to copy the Corresponding Source along with the object code. If the place to copy the object code is a network server, the Corresponding Source may be on a different server (operated by you or a third party) that supports equivalent copying facilities, provided you maintain clear directions next to the object code saying where to find the Corresponding Source. Regardless of what server hosts the Corresponding Source, you remain obligated to ensure that it is available for as long as needed to satisfy these requirements.
+
+ e) Convey the object code using peer-to-peer transmission, provided you inform other peers where the object code and Corresponding Source of the work are being offered to the general public at no charge under subsection 6d.
+
+A separable portion of the object code, whose source code is excluded from the Corresponding Source as a System Library, need not be included in conveying the object code work.
+
+A “User Product” is either (1) a “consumer product”, which means any tangible personal property which is normally used for personal, family, or household purposes, or (2) anything designed or sold for incorporation into a dwelling. In determining whether a product is a consumer product, doubtful cases shall be resolved in favor of coverage. For a particular product received by a particular user, “normally used” refers to a typical or common use of that class of product, regardless of the status of the particular user or of the way in which the particular user actually uses, or expects or is expected to use, the product. A product is a consumer product regardless of whether the product has substantial commercial, industrial or non-consumer uses, unless such uses represent the only significant mode of use of the product.
+
+“Installation Information” for a User Product means any methods, procedures, authorization keys, or other information required to install and execute modified versions of a covered work in that User Product from a modified version of its Corresponding Source. The information must suffice to ensure that the continued functioning of the modified object code is in no case prevented or interfered with solely because modification has been made.
+
+If you convey an object code work under this section in, or with, or specifically for use in, a User Product, and the conveying occurs as part of a transaction in which the right of possession and use of the User Product is transferred to the recipient in perpetuity or for a fixed term (regardless of how the transaction is characterized), the Corresponding Source conveyed under this section must be accompanied by the Installation Information. But this requirement does not apply if neither you nor any third party retains the ability to install modified object code on the User Product (for example, the work has been installed in ROM).
+
+The requirement to provide Installation Information does not include a requirement to continue to provide support service, warranty, or updates for a work that has been modified or installed by the recipient, or for the User Product in which it has been modified or installed. Access to a network may be denied when the modification itself materially and adversely affects the operation of the network or violates the rules and protocols for communication across the network.
+
+Corresponding Source conveyed, and Installation Information provided, in accord with this section must be in a format that is publicly documented (and with an implementation available to the public in source code form), and must require no special password or key for unpacking, reading or copying.
+
+7. Additional Terms.
+“Additional permissions” are terms that supplement the terms of this License by making exceptions from one or more of its conditions. Additional permissions that are applicable to the entire Program shall be treated as though they were included in this License, to the extent that they are valid under applicable law. If additional permissions apply only to part of the Program, that part may be used separately under those permissions, but the entire Program remains governed by this License without regard to the additional permissions.
+
+When you convey a copy of a covered work, you may at your option remove any additional permissions from that copy, or from any part of it. (Additional permissions may be written to require their own removal in certain cases when you modify the work.) You may place additional permissions on material, added by you to a covered work, for which you have or can give appropriate copyright permission.
+
+Notwithstanding any other provision of this License, for material you add to a covered work, you may (if authorized by the copyright holders of that material) supplement the terms of this License with terms:
+
+ a) Disclaiming warranty or limiting liability differently from the terms of sections 15 and 16 of this License; or
+
+ b) Requiring preservation of specified reasonable legal notices or author attributions in that material or in the Appropriate Legal Notices displayed by works containing it; or
+
+ c) Prohibiting misrepresentation of the origin of that material, or requiring that modified versions of such material be marked in reasonable ways as different from the original version; or
+
+ d) Limiting the use for publicity purposes of names of licensors or authors of the material; or
+
+ e) Declining to grant rights under trademark law for use of some trade names, trademarks, or service marks; or
+
+ f) Requiring indemnification of licensors and authors of that material by anyone who conveys the material (or modified versions of it) with contractual assumptions of liability to the recipient, for any liability that these contractual assumptions directly impose on those licensors and authors.
+
+All other non-permissive additional terms are considered “further restrictions” within the meaning of section 10. If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term. If a license document contains a further restriction but permits relicensing or conveying under this License, you may add to a covered work material governed by the terms of that license document, provided that the further restriction does not survive such relicensing or conveying.
+
+If you add terms to a covered work in accord with this section, you must place, in the relevant source files, a statement of the additional terms that apply to those files, or a notice indicating where to find the applicable terms.
+
+Additional terms, permissive or non-permissive, may be stated in the form of a separately written license, or stated as exceptions; the above requirements apply either way.
+
+8. Termination.
+You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11).
+
+However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.
+
+Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.
+
+Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, you do not qualify to receive new licenses for the same material under section 10.
+
+9. Acceptance Not Required for Having Copies.
+You are not required to accept this License in order to receive or run a copy of the Program. Ancillary propagation of a covered work occurring solely as a consequence of using peer-to-peer transmission to receive a copy likewise does not require acceptance. However, nothing other than this License grants you permission to propagate or modify any covered work. These actions infringe copyright if you do not accept this License. Therefore, by modifying or propagating a covered work, you indicate your acceptance of this License to do so.
+
+10. Automatic Licensing of Downstream Recipients.
+Each time you convey a covered work, the recipient automatically receives a license from the original licensors, to run, modify and propagate that work, subject to this License. You are not responsible for enforcing compliance by third parties with this License.
+
+An “entity transaction” is a transaction transferring control of an organization, or substantially all assets of one, or subdividing an organization, or merging organizations. If propagation of a covered work results from an entity transaction, each party to that transaction who receives a copy of the work also receives whatever licenses to the work the party's predecessor in interest had or could give under the previous paragraph, plus a right to possession of the Corresponding Source of the work from the predecessor in interest, if the predecessor has it or can get it with reasonable efforts.
+
+You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License. For example, you may not impose a license fee, royalty, or other charge for exercise of rights granted under this License, and you may not initiate litigation (including a cross-claim or counterclaim in a lawsuit) alleging that any patent claim is infringed by making, using, selling, offering for sale, or importing the Program or any portion of it.
+
+11. Patents.
+A “contributor” is a copyright holder who authorizes use under this License of the Program or a work on which the Program is based. The work thus licensed is called the contributor's “contributor version”.
+
+A contributor's “essential patent claims” are all patent claims owned or controlled by the contributor, whether already acquired or hereafter acquired, that would be infringed by some manner, permitted by this License, of making, using, or selling its contributor version, but do not include claims that would be infringed only as a consequence of further modification of the contributor version. For purposes of this definition, “control” includes the right to grant patent sublicenses in a manner consistent with the requirements of this License.
+
+Each contributor grants you a non-exclusive, worldwide, royalty-free patent license under the contributor's essential patent claims, to make, use, sell, offer for sale, import and otherwise run, modify and propagate the contents of its contributor version.
+
+In the following three paragraphs, a “patent license” is any express agreement or commitment, however denominated, not to enforce a patent (such as an express permission to practice a patent or covenant not to sue for patent infringement). To “grant” such a patent license to a party means to make such an agreement or commitment not to enforce a patent against the party.
+
+If you convey a covered work, knowingly relying on a patent license, and the Corresponding Source of the work is not available for anyone to copy, free of charge and under the terms of this License, through a publicly available network server or other readily accessible means, then you must either (1) cause the Corresponding Source to be so available, or (2) arrange to deprive yourself of the benefit of the patent license for this particular work, or (3) arrange, in a manner consistent with the requirements of this License, to extend the patent license to downstream recipients. “Knowingly relying” means you have actual knowledge that, but for the patent license, your conveying the covered work in a country, or your recipient's use of the covered work in a country, would infringe one or more identifiable patents in that country that you have reason to believe are valid.
+
+If, pursuant to or in connection with a single transaction or arrangement, you convey, or propagate by procuring conveyance of, a covered work, and grant a patent license to some of the parties receiving the covered work authorizing them to use, propagate, modify or convey a specific copy of the covered work, then the patent license you grant is automatically extended to all recipients of the covered work and works based on it.
+
+A patent license is “discriminatory” if it does not include within the scope of its coverage, prohibits the exercise of, or is conditioned on the non-exercise of one or more of the rights that are specifically granted under this License. You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of the parties who would receive the covered work from you, a discriminatory patent license (a) in connection with copies of the covered work conveyed by you (or copies made from those copies), or (b) primarily for and in connection with specific products or compilations that contain the covered work, unless you entered into that arrangement, or that patent license was granted, prior to 28 March 2007.
+
+Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law.
+
+12. No Surrender of Others' Freedom.
+If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program.
+
+13. Use with the GNU Affero General Public License.
+Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such.
+
+14. Revised Versions of this License.
+The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.
+
+Each version is given a distinguishing version number. If the Program specifies that a certain numbered version of the GNU General Public License “or any later version” applies to it, you have the option of following the terms and conditions either of that numbered version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of the GNU General Public License, you may choose any version ever published by the Free Software Foundation.
+
+If the Program specifies that a proxy can decide which future versions of the GNU General Public License can be used, that proxy's public statement of acceptance of a version permanently authorizes you to choose that version for the Program.
+
+Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version.
+
+15. Disclaimer of Warranty.
+THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+16. Limitation of Liability.
+IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+
+17. Interpretation of Sections 15 and 16.
+If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee.
+
+END OF TERMS AND CONDITIONS
+
+How to Apply These Terms to Your New Programs
+
+If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.
+
+To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
+
+
+ Copyright (C)
+
+ This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with this program. If not, see .
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:
+
+ Copyright (C)
+ This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, your program's commands might be different; for a GUI interface, you would use an “about box”.
+
+You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see .
+
+The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read .
diff --git a/euler/README.md b/euler/README.md
new file mode 100644
index 00000000..52dd88e3
--- /dev/null
+++ b/euler/README.md
@@ -0,0 +1,8 @@
+
+# About
+This crate is source code of solutions in [project euler][euler].
+
+![Badge][badge]
+
+[euler]: https://projecteuler.org
+[badge]: https://projecteuler.net/profile/xushaohua.png
diff --git a/euler/rust-toolchain.toml b/euler/rust-toolchain.toml
new file mode 100644
index 00000000..5d56faf9
--- /dev/null
+++ b/euler/rust-toolchain.toml
@@ -0,0 +1,2 @@
+[toolchain]
+channel = "nightly"
diff --git a/euler/rust/deprecated/bin/euler_003.rs b/euler/rust/deprecated/bin/euler_003.rs
new file mode 100644
index 00000000..d7d75e7f
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_003.rs
@@ -0,0 +1,94 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate euler;
+extern crate test;
+
+use euler::primes::get_prime_list;
+
+/// Problem:
+///
+/// The prime factors of 13195 are 5, 7, 13 and 29.
+/// What is the largest prime factor of the number 600851475143 ?
+
+const LARGEST_PRIME: u64 = 600851475143;
+
+fn method1(num: u64) -> u64 {
+ // Largest possible prime factor of an integer is its square root.
+ let sqrt: usize = (num as f64).sqrt().ceil() as usize;
+
+ // Now get prime list smaller than square root.
+ let prime_list = get_prime_list(sqrt);
+ for prime in prime_list.into_iter().rev() {
+ if num % (prime as u64) == 0 {
+ return prime as u64;
+ }
+ }
+
+ 0
+}
+
+fn method2(num: u64) -> u64 {
+ for i in 2..=num {
+ if num % i == 0 {
+ return if num == i { num } else { method2(num / i) };
+ }
+ }
+ 0
+}
+
+fn method3(mut num: u64) -> u64 {
+ let mut i = 2;
+ while i < num {
+ if num % i == 0 {
+ num /= i;
+ }
+ i += 1;
+ }
+ i
+}
+
+fn method4(mut num: u64) -> u64 {
+ let mut i = 2;
+ while i <= num {
+ if num % i == 0 {
+ num /= i;
+ } else {
+ if i == 2 {
+ i += 1;
+ } else {
+ i += 2;
+ }
+ }
+ }
+ i
+}
+
+fn main() {
+ println!("method1: {}", method1(LARGEST_PRIME));
+ println!("method2: {}", method2(LARGEST_PRIME));
+ println!("method3: {}", method3(LARGEST_PRIME));
+ println!("method4: {}", method4(LARGEST_PRIME));
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(LARGEST_PRIME), 6857));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(LARGEST_PRIME), 6857));
+}
+
+#[bench]
+fn bench_method3(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method3(LARGEST_PRIME), 6857));
+}
+
+#[bench]
+fn bench_method4(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method4(LARGEST_PRIME), 6857));
+}
diff --git a/euler/rust/deprecated/bin/euler_005.rs b/euler/rust/deprecated/bin/euler_005.rs
new file mode 100644
index 00000000..5eaf1612
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_005.rs
@@ -0,0 +1,49 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use std::cmp::max;
+
+use euler::primes::{get_prime_factors, get_prime_list, PrimeFactor};
+
+/// Problem:
+///
+/// 2520 is the smallest number that can be divided by each of the numbers from
+/// 1 to 10 without any remainder. What is the smallest positive number
+/// that is evenly divisible by all of the numbers from 1 to 20?
+
+fn method1(max_num: usize) -> usize {
+ let ls = get_prime_list(max_num);
+ let mut minimum_factors = Vec::with_capacity(ls.len());
+ for factor in &ls {
+ minimum_factors.push(PrimeFactor {
+ num: *factor,
+ count: 0,
+ });
+ }
+
+ for i in 2..=max_num {
+ let factors = get_prime_factors(i, &ls);
+ for factor in &factors {
+ for m in &mut minimum_factors {
+ if m.num == factor.num {
+ m.count = max(m.count, factor.count);
+ }
+ }
+ }
+ }
+
+ minimum_factors.iter().fold(1, |p, f| p * f.num.pow(f.count as u32))
+}
+
+fn main() {
+ println!("method1 {}", method1(20));
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(20), 232792560));
+}
\ No newline at end of file
diff --git a/euler/rust/deprecated/bin/euler_006.rs b/euler/rust/deprecated/bin/euler_006.rs
new file mode 100644
index 00000000..5822aa5a
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_006.rs
@@ -0,0 +1,56 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// The sum of the squares of the first ten natural numbers is,
+///
+/// 1^2 + 2^2 + ... + 10^2 = 385
+///
+/// The square of the sum of the first ten natural numbers is,
+/// (1 + 2 + ... + 10)^2 = 55^2 = 3025
+///
+/// Hence the difference between the sum of the squares of the first
+/// ten natural numbers and the square of the sum is 3025−385=2640 .
+///
+/// Find the difference between the sum of the squares of the first
+/// one hundred natural numbers and the square of the sum.
+
+fn method1(max_num: i64) -> i64 {
+ let mut square_sum = 0;
+ for i in 1..=max_num {
+ square_sum += i * i;
+ }
+
+ let mut sum = 0;
+ for i in 1..=max_num {
+ sum += i;
+ }
+ sum * sum - square_sum
+}
+
+fn method2(max_num: i64) -> i64 {
+ let square_sum: i64 = (1..=max_num).map(|i| i * i).sum();
+ let sum: i64 = (1..=max_num).sum();
+ sum * sum - square_sum
+}
+
+fn main() {
+ let max_num = 100;
+ println!("result: {}", method1(max_num));
+ println!("result: {}", method2(max_num));
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(100), 25164150));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(100), 25164150));
+}
diff --git a/euler/rust/deprecated/bin/euler_007.rs b/euler/rust/deprecated/bin/euler_007.rs
new file mode 100644
index 00000000..a299253f
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_007.rs
@@ -0,0 +1,51 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::primes::{get_prime_list, IsPrime};
+
+/// Problem:
+///
+/// By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see
+/// that the 6th prime is 13.
+///
+/// What is the 10 001st prime number?
+
+fn method1(nth_prime: u32) -> usize {
+ let prime_list = get_prime_list(110_000);
+ prime_list[nth_prime as usize - 1]
+}
+
+fn method2(nth_prime: u32) -> usize {
+ let mut primes = Vec::with_capacity(nth_prime as usize);
+ primes.push(2);
+ let mut num = 3;
+ while primes.len() < nth_prime as usize {
+ if num.is_prime() {
+ primes.push(num);
+ }
+
+ num += 2;
+ }
+
+ primes[primes.len() - 1]
+}
+
+fn main() {
+ let nth_prime = 10001;
+ println!("#10001 prime is: {}", method1(nth_prime));
+ println!("#10001 prime is: {}", method2(nth_prime));
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(10001), 104743));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(10001), 104743));
+}
diff --git a/euler/rust/deprecated/bin/euler_008.rs b/euler/rust/deprecated/bin/euler_008.rs
new file mode 100644
index 00000000..f272e93d
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_008.rs
@@ -0,0 +1,98 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// The four adjacent digits in the 1000-digit number that have
+/// the greatest product are 9 × 9 × 8 × 9 = 5832.
+///
+/// 73167176531330624919225119674426574742355349194934
+/// 96983520312774506326239578318016984801869478851843
+/// 85861560789112949495459501737958331952853208805511
+/// 12540698747158523863050715693290963295227443043557
+/// 66896648950445244523161731856403098711121722383113
+/// 62229893423380308135336276614282806444486645238749
+/// 30358907296290491560440772390713810515859307960866
+/// 70172427121883998797908792274921901699720888093776
+/// 65727333001053367881220235421809751254540594752243
+/// 52584907711670556013604839586446706324415722155397
+/// 53697817977846174064955149290862569321978468622482
+/// 83972241375657056057490261407972968652414535100474
+/// 82166370484403199890008895243450658541227588666881
+/// 16427171479924442928230863465674813919123162824586
+/// 17866458359124566529476545682848912883142607690042
+/// 24219022671055626321111109370544217506941658960408
+/// 07198403850962455444362981230987879927244284909188
+/// 84580156166097919133875499200524063689912560717606
+/// 05886116467109405077541002256983155200055935729725
+/// 71636269561882670428252483600823257530420752963450
+///
+/// Find the thirteen adjacent digits in the 1000-digit number
+/// that have the greatest product. What is the value of this product?
+
+const NUMS: &str = "
+73167176531330624919225119674426574742355349194934
+96983520312774506326239578318016984801869478851843
+85861560789112949495459501737958331952853208805511
+12540698747158523863050715693290963295227443043557
+66896648950445244523161731856403098711121722383113
+62229893423380308135336276614282806444486645238749
+30358907296290491560440772390713810515859307960866
+70172427121883998797908792274921901699720888093776
+65727333001053367881220235421809751254540594752243
+52584907711670556013604839586446706324415722155397
+53697817977846174064955149290862569321978468622482
+83972241375657056057490261407972968652414535100474
+82166370484403199890008895243450658541227588666881
+16427171479924442928230863465674813919123162824586
+17866458359124566529476545682848912883142607690042
+24219022671055626321111109370544217506941658960408
+07198403850962455444362981230987879927244284909188
+84580156166097919133875499200524063689912560717606
+05886116467109405077541002256983155200055935729725
+71636269561882670428252483600823257530420752963450
+";
+
+fn method1(nums: &[u8; 1000]) -> u64 {
+ let mut product: u64;
+ let last_pos: usize = 1000 - 13;
+ let mut largest_product: u64 = 1;
+ for i in 0..last_pos {
+ product = 1;
+ for num in nums.iter().skip(i).take(13) {
+ product *= *num as u64;
+ if product > largest_product {
+ largest_product = product;
+ }
+ }
+ }
+ largest_product
+}
+
+fn get_nums() -> [u8; 1000] {
+ let mut nums = [0_u8; 1000];
+ let mut i = 0;
+ for c in NUMS.bytes() {
+ if c >= b'0' && c <= b'9' {
+ let num: u8 = c - b'0';
+ nums[i] = num;
+ i += 1;
+ }
+ }
+ nums
+}
+
+fn main() {
+ let nums = get_nums();
+ println!("method1: {}", method1(&nums));
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ let nums = get_nums();
+ b.iter(|| assert_eq!(method1(&nums), 23514624000));
+}
diff --git a/euler/rust/deprecated/bin/euler_009.rs b/euler/rust/deprecated/bin/euler_009.rs
new file mode 100644
index 00000000..e1dbad76
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_009.rs
@@ -0,0 +1,37 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// A Pythagorean triplet is a set of three natural numbers, a < b < c, for which,
+/// a^2 + b^2 = c^2
+///
+/// For example, 3^2 + 4^2 = 9 + 16 = 2^5 = 52.
+/// There exists exactly one Pythagorean triplet for which a + b + c = 1000.
+/// Find the product abc.
+
+fn method1() -> u64 {
+ for c in 333..1000 {
+ for a in 1..c {
+ let b = 1000 - a - c;
+ if a * a + b * b == c * c {
+ println!(">: {}, {}, {}", a, b, c);
+ return a * b * c;
+ }
+ }
+ }
+ 0
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 31875000));
+}
diff --git a/euler/rust/deprecated/bin/euler_010.rs b/euler/rust/deprecated/bin/euler_010.rs
new file mode 100644
index 00000000..d76525de
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_010.rs
@@ -0,0 +1,26 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate euler;
+extern crate test;
+
+/// Problem:
+///
+/// The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
+/// Find the sum of all the primes below two million.
+
+fn method1() -> usize {
+ let primes = euler::primes::get_prime_list(2_000_000);
+ primes.iter().sum()
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 142913828922));
+}
diff --git a/euler/rust/deprecated/bin/euler_011.rs b/euler/rust/deprecated/bin/euler_011.rs
new file mode 100644
index 00000000..f861be53
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_011.rs
@@ -0,0 +1,126 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// In the 20×20 grid below, four numbers along a diagonal line
+/// have been marked in red.
+///
+/// 08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
+/// 49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
+/// 81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
+/// 52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
+/// 22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
+/// 24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
+/// 32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
+/// 67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
+/// 24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
+/// 21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
+/// 78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
+/// 16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
+/// 86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
+/// 19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
+/// 04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
+/// 88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
+/// 04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
+/// 20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
+/// 20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
+/// 01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
+///
+/// The product of these numbers is 26 × 63 × 78 × 14 = 1788696.
+///
+/// What is the greatest product of four adjacent numbers
+/// in the same direction (up, down, left, right, or diagonally)
+/// in the 20×20 grid?
+
+const MAX: usize = 400;
+const NUMS: [u8; MAX] = [
+ 8, 2, 22, 97, 38, 15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8, 49, 49, 99, 40,
+ 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 4, 56, 62, 0, 81, 49, 31, 73, 55, 79, 14, 29,
+ 93, 71, 40, 67, 53, 88, 30, 3, 49, 13, 36, 65, 52, 70, 95, 23, 4, 60, 11, 42, 69, 24, 68, 56,
+ 1, 32, 56, 71, 37, 2, 36, 91, 22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28,
+ 66, 33, 13, 80, 24, 47, 32, 60, 99, 3, 45, 2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50,
+ 32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70, 67, 26, 20, 68,
+ 2, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21, 24, 55, 58, 5, 66, 73, 99, 26,
+ 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72, 21, 36, 23, 9, 75, 0, 76, 44, 20, 45, 35, 14,
+ 0, 61, 33, 97, 34, 31, 33, 95, 78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 3, 80, 4, 62, 16, 14,
+ 9, 53, 56, 92, 16, 39, 5, 42, 96, 35, 31, 47, 55, 58, 88, 24, 0, 17, 54, 24, 36, 29, 85, 57,
+ 86, 56, 0, 48, 35, 71, 89, 7, 5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58, 19, 80, 81, 68,
+ 5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 4, 89, 55, 40, 4, 52, 8, 83, 97, 35, 99, 16,
+ 7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66, 88, 36, 68, 87, 57, 62, 20, 72, 3, 46, 33, 67,
+ 46, 55, 12, 32, 63, 93, 53, 69, 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32,
+ 40, 62, 76, 36, 20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 4, 36, 16,
+ 20, 73, 35, 29, 78, 31, 90, 1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 5, 54, 1, 70, 54, 71,
+ 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 1, 89, 19, 67, 48,
+];
+
+fn method1() -> u64 {
+ let get_right_value = |n: usize| -> u64 {
+ let n1 = n + 1;
+ let n2 = n1 + 1;
+ let n3 = n2 + 1;
+ if n3 < MAX {
+ (NUMS[n] as u64) * (NUMS[n1] as u64) * (NUMS[n2] as u64) * (NUMS[n3] as u64)
+ } else {
+ 1
+ }
+ };
+
+ let get_bottom_value = |n: usize| -> u64 {
+ let n1 = n + 20;
+ let n2 = n1 + 20;
+ let n3 = n2 + 20;
+ if n3 < MAX {
+ (NUMS[n] as u64) * (NUMS[n1] as u64) * (NUMS[n2] as u64) * (NUMS[n3] as u64)
+ } else {
+ 1
+ }
+ };
+
+ let get_bottom_left = |n: usize| -> u64 {
+ let n1 = n + 19;
+ let n2 = n1 + 19;
+ let n3 = n2 + 19;
+ if n1 < MAX && n2 < MAX && n3 < MAX {
+ (NUMS[n] as u64) * (NUMS[n1] as u64) * (NUMS[n2] as u64) * (NUMS[n3] as u64)
+ } else {
+ 1
+ }
+ };
+ let get_bottom_right = |n: usize| -> u64 {
+ let n1 = n + 21;
+ let n2 = n1 + 21;
+ let n3 = n2 + 21;
+ if n1 < MAX && n2 < MAX && n3 < MAX {
+ (NUMS[n] as u64) * (NUMS[n1] as u64) * (NUMS[n2] as u64) * (NUMS[n3] as u64)
+ } else {
+ 1
+ }
+ };
+
+ let mut largest_product: u64 = 1;
+ let mut product: u64;
+ for i in 0..MAX {
+ product = std::cmp::max(get_right_value(i), get_bottom_value(i));
+ product = std::cmp::max(product, get_bottom_right(i));
+ product = std::cmp::max(product, get_bottom_left(i));
+ if product > largest_product {
+ println!("> {}", product);
+ largest_product = product;
+ }
+ }
+ largest_product
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 70600674));
+}
diff --git a/euler/rust/deprecated/bin/euler_012.rs b/euler/rust/deprecated/bin/euler_012.rs
new file mode 100644
index 00000000..1d958412
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_012.rs
@@ -0,0 +1,90 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// The sequence of triangle numbers is generated by adding the natural numbers.
+/// So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28.
+/// The first ten terms would be:
+/// 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
+/// Let us list the factors of the first seven triangle numbers:
+/// 1: 1
+/// 3: 1,3
+/// 6: 1,2,3,6
+/// 10: 1,2,5,10
+/// 15: 1,3,5,15
+/// 21: 1,3,7,21
+/// 28: 1,2,4,7,14,28
+/// We can see that 28 is the first triangle number to have over five divisors.
+/// What is the value of the first triangle number to have over
+/// five hundred divisors?
+
+fn get_num_factors(n: usize, primes: &[usize]) -> u16 {
+ let prime_factors = euler::primes::get_prime_factors(n, primes);
+ let mut num_factors = 1;
+ for factor in &prime_factors {
+ num_factors *= factor.count + 1;
+ }
+
+ num_factors
+}
+
+/// Ref:
+/// * https://www.allmathtricks.com/factors-number/
+fn method1() -> usize {
+ //let f(n) = n * (n + 1) / 2;
+ let mut s = 0;
+ let primes = euler::primes::get_prime_list(100_000);
+ for i in 1.. {
+ s += i;
+ let num_factors = get_num_factors(s, &primes);
+ if num_factors > 500 {
+ return s;
+ }
+ }
+ 0
+}
+
+fn factor(num: u32) -> u32 {
+ let mut buffer = 0;
+
+ let mut i = 1;
+ while i * i < num {
+ if num % i == 0 {
+ buffer += 1;
+ }
+ i += 1;
+ }
+ buffer * 2
+}
+
+fn method2() -> u32 {
+ let mut trinum = 0;
+ for i in 1.. {
+ trinum += i;
+ if factor(trinum) >= 500 {
+ break;
+ }
+ }
+
+ trinum
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 76576500));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), 76576500));
+}
diff --git a/euler/rust/deprecated/bin/euler_013.rs b/euler/rust/deprecated/bin/euler_013.rs
new file mode 100644
index 00000000..4bad5f60
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_013.rs
@@ -0,0 +1,315 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// Work out the first ten digits of the sum of the following one-hundred
+/// 50-digit numbers.
+///
+/// 37107287533902102798797998220837590246510135740250
+/// 46376937677490009712648124896970078050417018260538
+/// 74324986199524741059474233309513058123726617309629
+/// 91942213363574161572522430563301811072406154908250
+/// 23067588207539346171171980310421047513778063246676
+/// 89261670696623633820136378418383684178734361726757
+/// 28112879812849979408065481931592621691275889832738
+/// 44274228917432520321923589422876796487670272189318
+/// 47451445736001306439091167216856844588711603153276
+/// 70386486105843025439939619828917593665686757934951
+/// 62176457141856560629502157223196586755079324193331
+/// 64906352462741904929101432445813822663347944758178
+/// 92575867718337217661963751590579239728245598838407
+/// 58203565325359399008402633568948830189458628227828
+/// 80181199384826282014278194139940567587151170094390
+/// 35398664372827112653829987240784473053190104293586
+/// 86515506006295864861532075273371959191420517255829
+/// 71693888707715466499115593487603532921714970056938
+/// 54370070576826684624621495650076471787294438377604
+/// 53282654108756828443191190634694037855217779295145
+/// 36123272525000296071075082563815656710885258350721
+/// 45876576172410976447339110607218265236877223636045
+/// 17423706905851860660448207621209813287860733969412
+/// 81142660418086830619328460811191061556940512689692
+/// 51934325451728388641918047049293215058642563049483
+/// 62467221648435076201727918039944693004732956340691
+/// 15732444386908125794514089057706229429197107928209
+/// 55037687525678773091862540744969844508330393682126
+/// 18336384825330154686196124348767681297534375946515
+/// 80386287592878490201521685554828717201219257766954
+/// 78182833757993103614740356856449095527097864797581
+/// 16726320100436897842553539920931837441497806860984
+/// 48403098129077791799088218795327364475675590848030
+/// 87086987551392711854517078544161852424320693150332
+/// 59959406895756536782107074926966537676326235447210
+/// 69793950679652694742597709739166693763042633987085
+/// 41052684708299085211399427365734116182760315001271
+/// 65378607361501080857009149939512557028198746004375
+/// 35829035317434717326932123578154982629742552737307
+/// 94953759765105305946966067683156574377167401875275
+/// 88902802571733229619176668713819931811048770190271
+/// 25267680276078003013678680992525463401061632866526
+/// 36270218540497705585629946580636237993140746255962
+/// 24074486908231174977792365466257246923322810917141
+/// 91430288197103288597806669760892938638285025333403
+/// 34413065578016127815921815005561868836468420090470
+/// 23053081172816430487623791969842487255036638784583
+/// 11487696932154902810424020138335124462181441773470
+/// 63783299490636259666498587618221225225512486764533
+/// 67720186971698544312419572409913959008952310058822
+/// 95548255300263520781532296796249481641953868218774
+/// 76085327132285723110424803456124867697064507995236
+/// 37774242535411291684276865538926205024910326572967
+/// 23701913275725675285653248258265463092207058596522
+/// 29798860272258331913126375147341994889534765745501
+/// 18495701454879288984856827726077713721403798879715
+/// 38298203783031473527721580348144513491373226651381
+/// 34829543829199918180278916522431027392251122869539
+/// 40957953066405232632538044100059654939159879593635
+/// 29746152185502371307642255121183693803580388584903
+/// 41698116222072977186158236678424689157993532961922
+/// 62467957194401269043877107275048102390895523597457
+/// 23189706772547915061505504953922979530901129967519
+/// 86188088225875314529584099251203829009407770775672
+/// 11306739708304724483816533873502340845647058077308
+/// 82959174767140363198008187129011875491310547126581
+/// 97623331044818386269515456334926366572897563400500
+/// 42846280183517070527831839425882145521227251250327
+/// 55121603546981200581762165212827652751691296897789
+/// 32238195734329339946437501907836945765883352399886
+/// 75506164965184775180738168837861091527357929701337
+/// 62177842752192623401942399639168044983993173312731
+/// 32924185707147349566916674687634660915035914677504
+/// 99518671430235219628894890102423325116913619626622
+/// 73267460800591547471830798392868535206946944540724
+/// 76841822524674417161514036427982273348055556214818
+/// 97142617910342598647204516893989422179826088076852
+/// 87783646182799346313767754307809363333018982642090
+/// 10848802521674670883215120185883543223812876952786
+/// 71329612474782464538636993009049310363619763878039
+/// 62184073572399794223406235393808339651327408011116
+/// 66627891981488087797941876876144230030984490851411
+/// 60661826293682836764744779239180335110989069790714
+/// 85786944089552990653640447425576083659976645795096
+/// 66024396409905389607120198219976047599490197230297
+/// 64913982680032973156037120041377903785566085089252
+/// 16730939319872750275468906903707539413042652315011
+/// 94809377245048795150954100921645863754710598436791
+/// 78639167021187492431995700641917969777599028300699
+/// 15368713711936614952811305876380278410754449733078
+/// 40789923115535562561142322423255033685442488917353
+/// 44889911501440648020369068063960672322193204149535
+/// 41503128880339536053299340368006977710650566631954
+/// 81234880673210146739058568557934581403627822703280
+/// 82616570773948327592232845941706525094512325230608
+/// 22918802058777319719839450180888072429661980811197
+/// 77158542502016545090413245809786882778948721859617
+/// 72107838435069186155435662884062257473692284509516
+/// 20849603980134001723930671666823555245252804609722
+/// 53503534226472524250874054075591789781264330331690
+
+const NUMS: [&str; 100] = [
+ "37107287533902102798797998220837590246510135740250",
+ "46376937677490009712648124896970078050417018260538",
+ "74324986199524741059474233309513058123726617309629",
+ "91942213363574161572522430563301811072406154908250",
+ "23067588207539346171171980310421047513778063246676",
+ "89261670696623633820136378418383684178734361726757",
+ "28112879812849979408065481931592621691275889832738",
+ "44274228917432520321923589422876796487670272189318",
+ "47451445736001306439091167216856844588711603153276",
+ "70386486105843025439939619828917593665686757934951",
+ "62176457141856560629502157223196586755079324193331",
+ "64906352462741904929101432445813822663347944758178",
+ "92575867718337217661963751590579239728245598838407",
+ "58203565325359399008402633568948830189458628227828",
+ "80181199384826282014278194139940567587151170094390",
+ "35398664372827112653829987240784473053190104293586",
+ "86515506006295864861532075273371959191420517255829",
+ "71693888707715466499115593487603532921714970056938",
+ "54370070576826684624621495650076471787294438377604",
+ "53282654108756828443191190634694037855217779295145",
+ "36123272525000296071075082563815656710885258350721",
+ "45876576172410976447339110607218265236877223636045",
+ "17423706905851860660448207621209813287860733969412",
+ "81142660418086830619328460811191061556940512689692",
+ "51934325451728388641918047049293215058642563049483",
+ "62467221648435076201727918039944693004732956340691",
+ "15732444386908125794514089057706229429197107928209",
+ "55037687525678773091862540744969844508330393682126",
+ "18336384825330154686196124348767681297534375946515",
+ "80386287592878490201521685554828717201219257766954",
+ "78182833757993103614740356856449095527097864797581",
+ "16726320100436897842553539920931837441497806860984",
+ "48403098129077791799088218795327364475675590848030",
+ "87086987551392711854517078544161852424320693150332",
+ "59959406895756536782107074926966537676326235447210",
+ "69793950679652694742597709739166693763042633987085",
+ "41052684708299085211399427365734116182760315001271",
+ "65378607361501080857009149939512557028198746004375",
+ "35829035317434717326932123578154982629742552737307",
+ "94953759765105305946966067683156574377167401875275",
+ "88902802571733229619176668713819931811048770190271",
+ "25267680276078003013678680992525463401061632866526",
+ "36270218540497705585629946580636237993140746255962",
+ "24074486908231174977792365466257246923322810917141",
+ "91430288197103288597806669760892938638285025333403",
+ "34413065578016127815921815005561868836468420090470",
+ "23053081172816430487623791969842487255036638784583",
+ "11487696932154902810424020138335124462181441773470",
+ "63783299490636259666498587618221225225512486764533",
+ "67720186971698544312419572409913959008952310058822",
+ "95548255300263520781532296796249481641953868218774",
+ "76085327132285723110424803456124867697064507995236",
+ "37774242535411291684276865538926205024910326572967",
+ "23701913275725675285653248258265463092207058596522",
+ "29798860272258331913126375147341994889534765745501",
+ "18495701454879288984856827726077713721403798879715",
+ "38298203783031473527721580348144513491373226651381",
+ "34829543829199918180278916522431027392251122869539",
+ "40957953066405232632538044100059654939159879593635",
+ "29746152185502371307642255121183693803580388584903",
+ "41698116222072977186158236678424689157993532961922",
+ "62467957194401269043877107275048102390895523597457",
+ "23189706772547915061505504953922979530901129967519",
+ "86188088225875314529584099251203829009407770775672",
+ "11306739708304724483816533873502340845647058077308",
+ "82959174767140363198008187129011875491310547126581",
+ "97623331044818386269515456334926366572897563400500",
+ "42846280183517070527831839425882145521227251250327",
+ "55121603546981200581762165212827652751691296897789",
+ "32238195734329339946437501907836945765883352399886",
+ "75506164965184775180738168837861091527357929701337",
+ "62177842752192623401942399639168044983993173312731",
+ "32924185707147349566916674687634660915035914677504",
+ "99518671430235219628894890102423325116913619626622",
+ "73267460800591547471830798392868535206946944540724",
+ "76841822524674417161514036427982273348055556214818",
+ "97142617910342598647204516893989422179826088076852",
+ "87783646182799346313767754307809363333018982642090",
+ "10848802521674670883215120185883543223812876952786",
+ "71329612474782464538636993009049310363619763878039",
+ "62184073572399794223406235393808339651327408011116",
+ "66627891981488087797941876876144230030984490851411",
+ "60661826293682836764744779239180335110989069790714",
+ "85786944089552990653640447425576083659976645795096",
+ "66024396409905389607120198219976047599490197230297",
+ "64913982680032973156037120041377903785566085089252",
+ "16730939319872750275468906903707539413042652315011",
+ "94809377245048795150954100921645863754710598436791",
+ "78639167021187492431995700641917969777599028300699",
+ "15368713711936614952811305876380278410754449733078",
+ "40789923115535562561142322423255033685442488917353",
+ "44889911501440648020369068063960672322193204149535",
+ "41503128880339536053299340368006977710650566631954",
+ "81234880673210146739058568557934581403627822703280",
+ "82616570773948327592232845941706525094512325230608",
+ "22918802058777319719839450180888072429661980811197",
+ "77158542502016545090413245809786882778948721859617",
+ "72107838435069186155435662884062257473692284509516",
+ "20849603980134001723930671666823555245252804609722",
+ "53503534226472524250874054075591789781264330331690",
+];
+
+fn method1(nums: &[&str]) -> u64 {
+ let mut digits = Vec::new();
+ let mut sum = 0;
+ for i in (0..50).rev() {
+ for num in nums {
+ if let Some(digit) = num.chars().nth(i) {
+ if let Some(digit) = digit.to_digit(10) {
+ sum += digit;
+ }
+ }
+ }
+ let remainder = sum % 10;
+ digits.push(remainder);
+ sum /= 10;
+ }
+ while sum > 0 {
+ let remainder = sum % 10;
+ digits.push(remainder);
+ sum /= 10;
+ }
+
+ digits
+ .into_iter()
+ .rev()
+ .take(10)
+ .fold(0, |sum: u64, digit: u32| {
+ sum * 10 + digit as u64
+ })
+}
+
+fn method2(nums: &[&str]) -> u64 {
+ let mut last_part: u128 = 0;
+ for num in nums {
+ let x: u128 = (&num[25..]).parse().expect("Failed to parse digits");
+ last_part += x;
+ }
+ let mut first_part: u128 = 0;
+ for num in nums {
+ let x: u128 = (&num[..25]).parse().expect("Failed to parse digits");
+ first_part += x;
+ }
+ let separator = 10_u128.pow(25);
+ first_part += last_part / (separator);
+ last_part %= separator;
+ (first_part.to_string() + &last_part.to_string())[..10].parse::().unwrap()
+}
+
+fn method3(nums: &[&str]) -> u64 {
+ let mut digits = Vec::with_capacity(60);
+ let mut sum = 0;
+ for i in (0..50).rev() {
+ for num in nums {
+ let digit: u32 = num[i..i + 1].parse().expect("Failed to read digit");
+ sum += digit;
+ }
+ let remainder = sum % 10;
+ digits.push(remainder);
+ sum /= 10;
+ }
+ while sum > 0 {
+ let remainder = sum % 10;
+ digits.push(remainder);
+ sum /= 10;
+ }
+
+ digits
+ .into_iter()
+ .rev()
+ .take(10)
+ .fold(0, |sum: u64, digit: u32| {
+ sum * 10 + digit as u64
+ })
+}
+
+fn main() {
+ println!("method1: {}", method1(&NUMS));
+ println!("method2 = {}", method2(&NUMS));
+ println!("method3 = {}", method3(&NUMS));
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(&NUMS), 5537376230));
+}
+
+#[bench]
+fn bench_method3(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method3(&NUMS), 5537376230));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(&NUMS), 5537376230));
+}
+
+#[test]
+fn test_method_eq() {
+ assert_eq!(method1(&NUMS), method2(&NUMS));
+}
diff --git a/euler/rust/deprecated/bin/euler_014.rs b/euler/rust/deprecated/bin/euler_014.rs
new file mode 100644
index 00000000..c0ffe541
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_014.rs
@@ -0,0 +1,104 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// The following iterative sequence is defined for the set of positive
+/// integers:
+///
+/// n → n/2 (n is even)
+/// n → 3n + 1 (n is odd)
+///
+/// Using the rule above and starting with 13, we generate the following
+/// sequence:
+///
+/// 13 → 40 → 20 → 10 → 5 → 16 → 8 → 4 → 2 → 1
+///
+/// It can be seen that this sequence (starting at 13 and finishing at 1)
+/// contains 10 terms. Although it has not been proved yet (Collatz Problem),
+/// it is thought that all starting numbers finish at 1.
+/// Which starting number, under one million, produces the longest chain?
+///
+/// NOTE: Once the chain starts the terms are allowed to go above one million.
+
+fn method1() -> u32 {
+ let get_collatz_sequence = |n: u32| -> u32 {
+ let mut n: u64 = n as u64;
+ let mut seq = 0;
+ while n != 1 {
+ if n % 2 == 0 {
+ n /= 2;
+ } else {
+ n = 3 * n + 1;
+ }
+ seq += 1;
+ }
+ seq
+ };
+
+ let mut largest_sequence = 0;
+ let mut largest_sequence_num = 0;
+ for i in 1..=1_000_000 {
+ let seq = get_collatz_sequence(i);
+ if seq > largest_sequence {
+ largest_sequence_num = i;
+ largest_sequence = seq;
+ }
+ }
+
+ largest_sequence_num
+}
+
+fn method2() -> usize {
+ const MAX: usize = 1_000_000;
+ let cache: [u32; MAX + 1] = [0; MAX + 1];
+ let get_collatz_sequence = |num: usize| -> u32 {
+ let mut n = num;
+ let mut seq = 0;
+ while n != 1 {
+ if n < num && cache[n] != 0 {
+ seq += cache[n];
+ break;
+ }
+ if n % 2 == 0 {
+ n /= 2;
+ } else {
+ n = 3 * n + 1;
+ }
+ seq += 1;
+ }
+ seq
+ };
+
+ let mut largest_sequence = 0;
+ let mut largest_sequence_num = 0;
+ for i in 1..=MAX {
+ let seq = get_collatz_sequence(i);
+ if seq > largest_sequence {
+ largest_sequence_num = i;
+ largest_sequence = seq;
+ }
+ }
+
+ largest_sequence_num
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 837799));
+}
+
+#[bench]
+fn bench_method2(_b: &mut test::Bencher) {
+ // FIXME(Shaohua): Stackoverflow
+ //b.iter(|| method2());
+}
diff --git a/euler/rust/deprecated/bin/euler_016.rs b/euler/rust/deprecated/bin/euler_016.rs
new file mode 100644
index 00000000..f63cbe2d
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_016.rs
@@ -0,0 +1,41 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// 2^15 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.
+/// What is the sum of the digits of the number 2^1000?
+
+fn method1() -> u32 {
+ const MAX: usize = 1000;
+ let mut digits: [u8; MAX] = [0; MAX];
+ digits[0] = 1;
+ for _ in 0..MAX {
+ let mut quotient = 0;
+ for digit in digits.iter_mut().take(MAX) {
+ quotient += *digit * 2;
+ if quotient >= 10 {
+ *digit = quotient - 10;
+ quotient = 1;
+ } else {
+ *digit = quotient;
+ quotient = 0;
+ }
+ }
+ }
+
+ digits.iter().map(|n| *n as u32).sum()
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 1366));
+}
diff --git a/euler/rust/deprecated/bin/euler_017.rs b/euler/rust/deprecated/bin/euler_017.rs
new file mode 100644
index 00000000..54ccbf1c
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_017.rs
@@ -0,0 +1,243 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use std::collections::HashMap;
+
+/// Problem:
+///
+/// If the numbers 1 to 5 are written out in words: one, two, three, four,
+/// five, then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total.
+/// If all the numbers from 1 to 1000 (one thousand) inclusive were
+/// written out in words, how many letters would be used?
+///
+/// NOTE: Do not count spaces or hyphens. For example, 342
+/// (three hundred and forty-two) contains 23 letters and
+/// 115 (one hundred and fifteen) contains 20 letters. The use of "and"
+/// when writing out numbers is in compliance with British usage.
+
+const LETTERS: [(u32, &str); 27] = [
+ (1, "one"),
+ (2, "two"),
+ (3, "three"),
+ (4, "four"),
+ (5, "five"),
+ (6, "six"),
+ (7, "seven"),
+ (8, "eight"),
+ (9, "nine"),
+ (10, "ten"),
+ (11, "eleven"),
+ (12, "twelve"),
+ (13, "thirteen"),
+ (14, "fourteen"),
+ (15, "fifteen"),
+ (16, "sixteen"),
+ (17, "seventeen"),
+ (18, "eighteen"),
+ (19, "nineteen"),
+ (20, "twenty"),
+ (30, "thirty"),
+ (40, "forty"),
+ (50, "fifty"),
+ (60, "sixty"),
+ (70, "seventy"),
+ (80, "eighty"),
+ (90, "ninety"),
+];
+
+fn method1() -> usize {
+ let mut letters = HashMap::new();
+ for letter in &LETTERS {
+ letters.insert(letter.0, letter.1.to_string());
+ }
+
+ let get_letters = |num: u32| -> usize {
+ let mut sum = Vec::new();
+ let mut n = num;
+ if n >= 1000 {
+ let quotient = n / 1000;
+ n %= 1000;
+ if let Some(l) = letters.get("ient) {
+ sum.push(l.clone());
+ } else {
+ panic!("letters not contain: {}", quotient);
+ }
+ sum.push("thousand".to_string());
+ }
+ if n >= 100 {
+ let quotient = n / 100;
+ n %= 100;
+
+ if let Some(l) = letters.get("ient) {
+ sum.push(l.clone());
+ } else {
+ panic!("letters not contain: {}", quotient);
+ }
+ sum.push("hundred".to_string());
+ if n > 0 {
+ sum.push("and".to_string());
+ }
+ }
+ if n >= 20 {
+ let quotient = n / 10 * 10;
+ if let Some(l) = letters.get("ient) {
+ sum.push(l.clone());
+ } else {
+ panic!("letters not contain: {}", quotient);
+ }
+ n %= 10;
+ } else if n >= 10 {
+ if let Some(l) = letters.get(&n) {
+ sum.push(l.clone());
+ } else {
+ panic!("letters not contain: {}", n);
+ }
+ }
+
+ if n > 0 && n < 10 {
+ if let Some(l) = letters.get(&n) {
+ sum.push(l.clone());
+ } else {
+ panic!("letters not contain: {}", n);
+ }
+ }
+
+ sum.iter().map(|word| word.len()).sum()
+ };
+
+ (1..=1000).map(get_letters).sum()
+}
+
+fn method2() -> usize {
+ let mut letters = HashMap::new();
+ for letter in &LETTERS {
+ letters.insert(letter.0, letter.1.len());
+ }
+
+ let get_letters = |num: u32| -> usize {
+ let mut sum = 0;
+ let mut n = num;
+ if n >= 1000 {
+ let quotient = n / 1000;
+ n %= 1000;
+ if let Some(l) = letters.get("ient) {
+ sum += l;
+ } else {
+ panic!("letters not contain: {}", quotient);
+ }
+ sum += "thousand".len();
+ }
+ if n >= 100 {
+ let quotient = n / 100;
+ n %= 100;
+
+ if let Some(l) = letters.get("ient) {
+ sum += l;
+ } else {
+ panic!("letters not contain: {}", quotient);
+ }
+ sum += "hundred".len();
+ if n > 0 {
+ sum += "and".len();
+ }
+ }
+ if n >= 20 {
+ let quotient = n / 10 * 10;
+ if let Some(l) = letters.get("ient) {
+ sum += l;
+ } else {
+ panic!("letters not contain: {}", quotient);
+ }
+ n %= 10;
+ } else if n >= 10 {
+ if let Some(l) = letters.get(&n) {
+ sum += l;
+ } else {
+ panic!("letters not contain: {}", n);
+ }
+ }
+
+ if n > 0 && n < 10 {
+ if let Some(l) = letters.get(&n) {
+ sum += l;
+ } else {
+ panic!("letters not contain: {}", n);
+ }
+ }
+ sum
+ };
+
+ (1..=1000).map(get_letters).sum()
+}
+
+fn method3() -> usize {
+ let mut letters = HashMap::new();
+ for letter in &LETTERS {
+ letters.insert(letter.0, letter.1.len());
+ }
+
+ let get_letters = |num: u32| -> usize {
+ let mut sum = 0;
+ let mut n = num;
+ let mut quotient;
+ if n >= 1000 {
+ quotient = n / 1000;
+ sum += letters["ient];
+ sum += "thousand".len();
+ n %= 1000;
+ }
+ if n >= 100 {
+ quotient = n / 100;
+ sum += letters["ient];
+ sum += "hundred".len();
+
+ n %= 100;
+ if n > 0 {
+ sum += "and".len();
+ }
+ }
+ if n >= 20 {
+ quotient = n / 10 * 10;
+ sum += letters["ient];
+ n %= 10;
+ } else if n >= 10 {
+ sum += letters[&n];
+ }
+
+ if n > 0 && n < 10 {
+ sum += letters[&n];
+ }
+ sum
+ };
+
+ let mut sum = 0;
+ for i in 1..=1000 {
+ sum += get_letters(i);
+ }
+ sum
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+ println!("method3: {}", method3());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 21124));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), 21124));
+}
+
+#[bench]
+fn bench_method3(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method3(), 21124));
+}
diff --git a/euler/rust/deprecated/bin/euler_018.rs b/euler/rust/deprecated/bin/euler_018.rs
new file mode 100644
index 00000000..229dbd64
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_018.rs
@@ -0,0 +1,52 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// By starting at the top of the triangle below and moving to adjacent
+/// numbers on the row below, the maximum total from top to bottom is 23.
+/// 3
+/// 7 4
+/// 2 4 6
+/// 8 5 9 3
+///
+/// That is, 3 + 7 + 4 + 9 = 23.
+/// Find the maximum total from top to bottom of the triangle below:
+///
+/// 75
+/// 95 64
+/// 17 47 82
+/// 18 35 87 10
+/// 20 04 82 47 65
+/// 19 01 23 75 03 34
+/// 88 02 77 73 07 63 67
+/// 99 65 04 28 06 16 70 92
+/// 41 41 26 56 83 40 80 70 33
+/// 41 48 72 33 47 32 37 16 94 29
+/// 53 71 44 65 25 43 91 52 97 51 14
+/// 70 11 33 28 77 73 17 78 39 68 17 57
+/// 91 71 52 38 17 14 91 43 58 50 27 29 48
+/// 63 66 04 68 89 53 67 30 73 16 69 87 40 31
+/// 04 62 98 27 23 09 70 98 73 93 38 53 60 04 23
+///
+/// NOTE: As there are only 16384 routes, it is possible to solve this problem
+/// by trying every route. However, Problem 67, is the same challenge with
+/// a triangle containing one-hundred rows; it cannot be solved by brute force,
+/// and requires a clever method! ;o)
+
+fn method1() -> u64 {
+ 0
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| method1());
+}
diff --git a/euler/rust/deprecated/bin/euler_019.rs b/euler/rust/deprecated/bin/euler_019.rs
new file mode 100644
index 00000000..1a561256
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_019.rs
@@ -0,0 +1,89 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// You are given the following information, but you may prefer to do
+/// some research for yourself.
+///
+/// * 1 Jan 1900 was a Monday.
+/// * Thirty days has September,
+/// April, June and November.
+/// All the rest have thirty-one,
+/// Saving February alone,
+/// Which has twenty-eight, rain or shine.
+/// And on leap years, twenty-nine.
+/// * A leap year occurs on any year evenly divisible by 4, but not on
+/// a century unless it is divisible by 400.
+///
+/// How many Sundays fell on the first of the month during the twentieth
+/// century (1 Jan 1901 to 31 Dec 2000)?
+
+type Year = u32;
+type Month = u8;
+type Day = u8;
+
+fn method1() -> u64 {
+ const MONTH_DAYS: [Month; 12] = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
+
+ let check_leap_year = |year: Year| year % 400 == 0 || (year % 4 == 0 && year % 100 != 0);
+
+ let mut year: Year = 1900;
+ let mut month: Month = 0; // January
+ let mut day: Day = 1; // zero-day
+ let mut weekday: u8 = 1; // Monday
+ let mut is_leap_year = check_leap_year(year);
+ let mut month_days = MONTH_DAYS[month as usize];
+
+ let mut count = 0;
+
+ loop {
+ if weekday == 7 && day == 1 && year > 1900 {
+ count += 1;
+ }
+
+ day += 1;
+ weekday %= 7;
+ weekday += 1;
+
+ if month_days < day {
+ // goto next month.
+ day = 1;
+ month += 1;
+ }
+
+ if month == 12 {
+ day = 1;
+ month = 0;
+ year += 1;
+ is_leap_year = check_leap_year(year);
+ }
+
+ if day == 1 {
+ month_days = MONTH_DAYS[month as usize];
+ // Handle leap years.
+ if month == 1 && is_leap_year {
+ month_days += 1;
+ }
+ }
+
+ if year == 2001 {
+ break;
+ }
+ }
+
+ count
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 171));
+}
diff --git a/euler/rust/deprecated/bin/euler_020.rs b/euler/rust/deprecated/bin/euler_020.rs
new file mode 100644
index 00000000..094346ed
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_020.rs
@@ -0,0 +1,41 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// n! means n × (n − 1) × ... × 3 × 2 × 1
+///
+/// For example, 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800,
+/// and the sum of the digits in the number 10! is
+/// 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.
+///
+/// Find the sum of the digits in the number 100!
+
+fn method1() -> u16 {
+ const MAX: usize = 1024;
+ let mut digits: [u16; MAX] = [0; MAX];
+ digits[0] = 1;
+ for i in 1..=100 {
+ let mut quotient = 0;
+ for j in 0..MAX {
+ quotient += digits[j] * i;
+ digits[j] = quotient % 10;
+ quotient /= 10;
+ }
+ }
+
+ digits.iter().sum()
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 648));
+}
diff --git a/euler/rust/deprecated/bin/euler_021.rs b/euler/rust/deprecated/bin/euler_021.rs
new file mode 100644
index 00000000..13df0435
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_021.rs
@@ -0,0 +1,50 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::primes::GetFactors;
+
+/// Problem:
+///
+/// Let d(n) be defined as the sum of proper divisors of n (numbers less than
+/// n which divide evenly into n).
+/// If d(a) = b and d(b) = a, where a ≠ b, then a and b are an amicable pair
+/// and each of a and b are called amicable numbers.
+///
+/// For example, the proper divisors of 220 are 1, 2, 4, 5, 10, 11, 20, 22,
+/// 44, 55 and 110; therefore d(220) = 284. The proper divisors of 284
+/// are 1, 2, 4, 71 and 142; so d(284) = 220.
+///
+/// Evaluate the sum of all the amicable numbers under 10000.
+
+fn method1() -> usize {
+ const MAX: usize = 10_000;
+
+ let mut divisors: [usize; MAX + 1] = [0; MAX + 1];
+
+ for i in 2..=MAX {
+ let divisor = i.get_factors().iter().sum();
+ divisors[i] = divisor;
+ }
+
+ let mut sum = 0;
+ for (index, divisor) in divisors.iter().enumerate() {
+ if index != *divisor && divisor <= &MAX && divisors[*divisor] == index {
+ sum += index;
+ }
+ }
+
+ sum
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 31626));
+}
diff --git a/euler/rust/deprecated/bin/euler_022.rs b/euler/rust/deprecated/bin/euler_022.rs
new file mode 100644
index 00000000..d0f74c41
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_022.rs
@@ -0,0 +1,63 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use std::fs::File;
+use std::io::{BufReader, Read};
+
+/// Problem:
+///
+/// Using names.txt (right click and 'Save Link/Target As...'), a 46K
+/// text file containing over five-thousand first names, begin by sorting it
+/// into alphabetical order. Then working out the alphabetical value for
+/// each name, multiply this value by its alphabetical position in the list
+/// to obtain a name score.
+///
+/// For example, when the list is sorted into alphabetical order, COLIN,
+/// which is worth 3 + 15 + 12 + 9 + 14 = 53, is the 938th name in the list.
+/// So, COLIN would obtain a score of 938 × 53 = 49714.
+///
+/// What is the total of all the name scores in the file?
+
+fn method1(words: &[String]) -> u64 {
+ let mut scores = 0;
+ for (index, word) in words.iter().enumerate() {
+ let word_score: u64 = word
+ .bytes()
+ .filter(|c| c != &b'"')
+ .map(|c| (c - b'A' + 1) as u64)
+ .sum();
+
+ scores += (index as u64 + 1) * word_score;
+ }
+ scores
+}
+
+fn read_file() -> Option> {
+ if let Some(file_path) = std::env::args_os().nth(1) {
+ let file = File::open(file_path).unwrap();
+ let mut buffer = BufReader::new(file);
+ let mut content = String::new();
+ buffer.read_to_string(&mut content).unwrap();
+ let mut words: Vec = content.split(',').map(|s| s.to_string()).collect();
+ words.sort();
+ Some(words)
+ } else {
+ eprintln!("Usage: {} file_path", std::env::args().next().unwrap());
+ None
+ }
+}
+
+fn main() {
+ let words = read_file().unwrap();
+ println!("method1: {}", method1(words.as_ref()));
+}
+
+#[bench]
+fn bench_method1(_b: &mut test::Bencher) {
+ // let words = read_file().unwrap();
+ // b.iter(|| method1(words.as_ref()));
+}
diff --git a/euler/rust/deprecated/bin/euler_023.rs b/euler/rust/deprecated/bin/euler_023.rs
new file mode 100644
index 00000000..bbc93c54
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_023.rs
@@ -0,0 +1,72 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::primes::GetFactors;
+
+/// Problem:
+///
+/// A perfect number is a number for which the sum of its proper divisors
+/// is exactly equal to the number. For example, the sum of the proper divisors
+/// of 28 would be 1 + 2 + 4 + 7 + 14 = 28, which means that 28 is a perfect
+/// number.
+///
+/// A number n is called deficient if the sum of its proper divisors is
+/// less than n and it is called abundant if this sum exceeds n.
+///
+/// As 12 is the smallest abundant number, 1 + 2 + 3 + 4 + 6 = 16, the smallest
+/// number that can be written as the sum of two abundant numbers is 24.
+/// By mathematical analysis, it can be shown that all integers greater than
+/// 28123 can be written as the sum of two abundant numbers. However,
+/// this upper limit cannot be reduced any further by analysis even though
+/// it is known that the greatest number that cannot be expressed as the sum
+/// of two abundant numbers is less than this limit.
+///
+/// Find the sum of all the positive integers which cannot be written as
+/// the sum of two abundant numbers.
+
+fn method1() -> u32 {
+ // TODO(Shaohua): Tuning method1
+ let max = 28123;
+ let mut buf = Vec::new();
+ let abundant_nums: Vec = (2_u32..max)
+ .filter(|i| {
+ i.get_factors_cache(&mut buf);
+ let sum: u32 = buf.iter().sum();
+ &sum > i
+ })
+ .collect();
+
+ let mut sum = 0;
+ for i in 1..=max {
+ let half = i / 2 + 1;
+ let mut exists = false;
+ for j in &abundant_nums {
+ if j > &half {
+ break;
+ }
+ let d = i - j;
+ if abundant_nums.binary_search(&d).is_ok() {
+ exists = true;
+ break;
+ }
+ }
+ if !exists {
+ sum += i;
+ }
+ }
+
+ sum
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 4179871));
+}
diff --git a/euler/rust/deprecated/bin/euler_024.rs b/euler/rust/deprecated/bin/euler_024.rs
new file mode 100644
index 00000000..8a990a8c
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_024.rs
@@ -0,0 +1,33 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// A permutation is an ordered arrangement of objects. For example,
+/// 3124 is one possible permutation of the digits 1, 2, 3 and 4.
+/// If all of the permutations are listed numerically or alphabetically,
+/// we call it lexicographic order. The lexicographic permutations of
+/// 0, 1 and 2 are:
+///
+/// 012 021 102 120 201 210
+///
+/// What is the millionth lexicographic permutation of the digits
+/// 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9?
+
+fn method1() -> u64 {
+ // FIXME(Shaohua): Move example code to here
+ 2783915460
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 2783915460));
+}
diff --git a/euler/rust/deprecated/bin/euler_025.rs b/euler/rust/deprecated/bin/euler_025.rs
new file mode 100644
index 00000000..2fbdab29
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_025.rs
@@ -0,0 +1,163 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// The Fibonacci sequence is defined by the recurrence relation:
+/// Fn = F_(n−1) + F_(n−2), where F1 = 1 and F2 = 1.
+/// Hence the first 12 terms will be:
+/// F1 = 1
+/// F2 = 1
+/// F3 = 2
+/// F4 = 3
+/// F5 = 5
+/// F6 = 8
+/// F7 = 13
+/// F8 = 21
+/// F9 = 34
+/// F10 = 55
+/// F11 = 89
+/// F12 = 144
+/// The 12th term, F12, is the first term to contain three digits.
+/// What is the index of the first term in the Fibonacci sequence to
+/// contain 1000 digits?
+
+fn method1() -> u32 {
+ const MAX_NUM: usize = 1000;
+ let mut a: Vec = Vec::with_capacity(MAX_NUM);
+ let mut b: Vec = Vec::with_capacity(MAX_NUM);
+ let mut digits = 1;
+ a.push(1);
+ b.push(1);
+ let mut index = 2;
+ loop {
+ index += 1;
+ let mut sum = 0;
+ let mut add_digit = false;
+ for digit in 0..digits {
+ sum += a[digit] + b[digit];
+ a[digit] = b[digit];
+ if sum > 9 {
+ b[digit] = sum - 10;
+ sum = 1;
+ add_digit = true;
+ } else {
+ b[digit] = sum;
+ sum = 0;
+ add_digit = false;
+ }
+ }
+ if add_digit {
+ b.push(1);
+ a.push(0);
+ digits += 1;
+ }
+ if (digits + 1) > MAX_NUM {
+ break;
+ }
+ }
+ index
+}
+
+fn method2() -> u32 {
+ const MAX_NUM: usize = 1000;
+ let mut a: Vec = Vec::with_capacity(MAX_NUM + 1);
+ let mut b: Vec = Vec::with_capacity(MAX_NUM + 1);
+ for _i in 0..MAX_NUM {
+ a.push(0);
+ b.push(0);
+ }
+ let mut digits = 1;
+ a[0] = 1;
+ b[0] = 1;
+ let mut index = 2;
+ loop {
+ index += 1;
+ let mut sum = 0;
+ let mut add_digit = false;
+ for digit in 0..digits {
+ sum += a[digit] + b[digit];
+ a[digit] = b[digit];
+ if sum > 9 {
+ b[digit] = sum - 10;
+ sum = 1;
+ add_digit = true;
+ } else {
+ b[digit] = sum;
+ sum = 0;
+ add_digit = false;
+ }
+ }
+ if add_digit {
+ b[digits] = 1;
+ digits += 1;
+ }
+ if (digits + 1) > MAX_NUM {
+ break;
+ }
+ }
+ index
+}
+
+fn method3() -> u32 {
+ const MAX_NUM: usize = 1000;
+ let mut a: [u8; MAX_NUM] = [0; MAX_NUM];
+ let mut b: [u8; MAX_NUM] = [0; MAX_NUM];
+ let mut digits = 1;
+ a[0] = 1;
+ b[0] = 1;
+
+ let mut index = 2;
+ let mut sum;
+ loop {
+ index += 1;
+ sum = 0;
+ let mut add_digit = false;
+ for digit in 0..digits {
+ sum += a[digit] + b[digit];
+ a[digit] = b[digit];
+ if sum > 9 {
+ b[digit] = sum - 10;
+ sum = 1;
+ add_digit = true;
+ } else {
+ b[digit] = sum;
+ sum = 0;
+ add_digit = false;
+ }
+ }
+ if add_digit {
+ b[digits] = 1;
+ digits += 1;
+ }
+ if (digits + 1) > MAX_NUM {
+ break;
+ }
+ }
+ index
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+ println!("method3: {}", method3());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 4782));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), 4782));
+}
+
+#[bench]
+fn bench_method3(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method3(), 4782));
+}
diff --git a/euler/rust/deprecated/bin/euler_026.rs b/euler/rust/deprecated/bin/euler_026.rs
new file mode 100644
index 00000000..d1783e68
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_026.rs
@@ -0,0 +1,70 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// A unit fraction contains 1 in the numerator. The decimal
+/// representation of the unit fractions with denominators 2 to 10
+/// are given:
+///
+/// 1/2 = 0.5
+/// 1/3 = 0.(3)
+/// 1/4 = 0.25
+/// 1/5 = 0.2
+/// 1/6 = 0.1(6)
+/// 1/7 = 0.(142857)
+/// 1/8 = 0.125
+/// 1/9 = 0.(1)
+/// 1/10 = 0.1
+///
+/// Where 0.1(6) means 0.166666..., and has a 1-digit recurring cycle.
+/// It can be seen that 1/7 has a 6-digit recurring cycle.
+///
+/// Find the value of d < 1000 for which 1/d contains the longest
+/// recurring cycle in its decimal fraction part.
+
+fn method1() -> u32 {
+ let mut longest_cycle = 1;
+ let mut longest_cycle_num = 0;
+
+ let mut buf = vec![];
+ let mut get_cycle = |i: u32| -> usize {
+ buf.clear();
+ let mut num = 1;
+ loop {
+ let r = (num % i) * 10;
+ if r == 0 {
+ return 0;
+ }
+ if let Some(index) = buf.iter().position(|n| n == &r) {
+ return buf.len() - index;
+ }
+ buf.push(r);
+ num = r;
+ }
+ };
+
+ for i in 2..1000 {
+ let cycle = get_cycle(i);
+ if cycle > longest_cycle {
+ //println!("> {} => {}, longest: {}", i, cycle, longest_cycle);
+ longest_cycle = cycle;
+ longest_cycle_num = i;
+ }
+ }
+
+ longest_cycle_num
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 983));
+}
diff --git a/euler/rust/deprecated/bin/euler_027.rs b/euler/rust/deprecated/bin/euler_027.rs
new file mode 100644
index 00000000..b5a9c9ae
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_027.rs
@@ -0,0 +1,104 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::primes::get_prime_list;
+
+/// Problem:
+/// Euler discovered the remarkable quadratic formula:
+/// n^2 + n + 41
+///
+/// It turns out that the formula will produce 40 primes for the consecutive
+/// integer values 0 ≤ n ≤ 39. However, when n = 40,
+/// 40^2 + 40 + 41 = 40(40 + 1) + 41 is divisible by 41, and certainly
+/// when n = 41,41^2 + 41 + 41 is clearly divisible by 41.
+///
+/// The incredible formula n^2 − 79^n + 1601 was discovered, which produces
+/// 80 primes for the consecutive values 0 ≤ n ≤ 79. The product of
+/// the coefficients, −79 and 1601, is −126479.
+///
+/// Considering quadratics of the form:
+///
+/// n^2 + an + b, where |a| < 1000 and |b| ≤ 1000
+/// where |n| is the modulus/absolute value of n
+/// e.g. |11| = 11 and |−4| = 4
+///
+/// Find the product of the coefficients, a and b, for the quadratic expression
+/// that produces the maximum number of primes for consecutive values of n,
+/// starting with n = 0.
+
+fn method1() -> i32 {
+ let prime_list = get_prime_list(2_300_000);
+ let mut coefficients = 0;
+ let mut max_num_primes = 0;
+
+ let is_product = |n: i32| prime_list.binary_search(&(n as usize)).is_ok();
+ let b_primes = get_prime_list(1000);
+
+ for a in -999..1000_i32 {
+ for b in &b_primes {
+ let mut num_primes = 0;
+ let b = *b as i32;
+ for i in 0.. {
+ let product = i * i + a * i + b;
+ if is_product(product) {
+ num_primes += 1;
+ } else {
+ break;
+ }
+ }
+
+ if num_primes > max_num_primes {
+ max_num_primes = num_primes;
+ coefficients = a * b;
+ }
+ }
+ }
+ coefficients
+}
+
+fn method2() -> i32 {
+ let prime_list = get_prime_list(2_300_000);
+ let mut coefficients = 0;
+ let mut max_num_primes = 0;
+
+ let is_product = |n: i32| prime_list.binary_search(&(n as usize)).is_ok();
+
+ for a in -999..1000_i32 {
+ for b in 2..1000 {
+ let mut num_primes = 0;
+ for i in 0.. {
+ let product = i * i + a * i + b;
+ if is_product(product) {
+ num_primes += 1;
+ } else {
+ break;
+ }
+ }
+
+ if num_primes > max_num_primes {
+ max_num_primes = num_primes;
+ coefficients = a * b;
+ }
+ }
+ }
+ coefficients
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), -59231));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), -59231));
+}
diff --git a/euler/rust/deprecated/bin/euler_028.rs b/euler/rust/deprecated/bin/euler_028.rs
new file mode 100644
index 00000000..56ee33f2
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_028.rs
@@ -0,0 +1,45 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// Starting with the number 1 and moving to the right in a clockwise direction
+/// a 5 by 5 spiral is formed as follows:
+///
+/// 21 22 23 24 25
+/// 20 7 8 9 10
+/// 19 6 1 2 11
+/// 18 5 4 3 12
+/// 17 16 15 14 13
+///
+/// It can be verified that the sum of the numbers on the diagonals is 101.
+///
+/// What is the sum of the numbers on the diagonals in a 1001 by 1001
+/// spiral formed in the same way?
+
+fn method1() -> u32 {
+ let mut sum = 1;
+ for i in 1.. {
+ let side = 2 * i + 1;
+ if side > 1001 {
+ break;
+ }
+ let s = side * side * 4 - i * 12;
+ //println!("side: {}, s: {}", side, s);
+ sum += s;
+ }
+ sum
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 669171001));
+}
diff --git a/euler/rust/deprecated/bin/euler_029.rs b/euler/rust/deprecated/bin/euler_029.rs
new file mode 100644
index 00000000..03bd6e41
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_029.rs
@@ -0,0 +1,51 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate num_bigint;
+extern crate test;
+
+use num_bigint::BigUint;
+use std::collections::HashSet;
+
+/// Problem:
+///
+/// Consider all integer combinations of ab for 2 ≤ a ≤ 5 and 2 ≤ b ≤ 5:
+///
+/// 2^2=4, 2^3=8, 2^4=16, 2^5=32
+/// 3^2=9, 3^3=27, 3^4=81, 3^5=243
+/// 4^2=16, 4^3=64, 4^4=256, 4^5=1024
+/// 5^2=25, 5^3=125, 5^4=625, 5^5=3125
+///
+/// If they are then placed in numerical order, with any repeats removed,
+/// we get the following sequence of 15 distinct terms:
+///
+/// 4, 8, 9, 16, 25, 27, 32, 64, 81, 125, 243, 256, 625, 1024, 3125
+///
+/// How many distinct terms are in the sequence generated by ab for
+/// 2 ≤ a ≤ 100 and 2 ≤ b ≤ 100?
+
+fn method1() -> usize {
+ let mut set = HashSet::::new();
+
+ let mut big_num: BigUint;
+ for i in 2_u16..=100 {
+ big_num = BigUint::from(i);
+ for _j in 2_u16..=100 {
+ big_num *= i;
+ set.insert(big_num.to_string());
+ }
+ }
+
+ set.len()
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 9183));
+}
diff --git a/euler/rust/deprecated/bin/euler_030.rs b/euler/rust/deprecated/bin/euler_030.rs
new file mode 100644
index 00000000..2b4303e8
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_030.rs
@@ -0,0 +1,129 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// Surprisingly there are only three numbers that can be written as
+/// the sum of fourth powers of their digits:
+///
+/// 1634 = 14 + 64 + 34 + 44
+/// 8208 = 84 + 24 + 04 + 84
+/// 9474 = 94 + 44 + 74 + 44
+///
+/// As 1 = 14 is not a sum it is not included.
+///
+/// The sum of these numbers is 1634 + 8208 + 9474 = 19316.
+///
+/// Find the sum of all the numbers that can be written as
+/// the sum of fifth powers of their digits.
+
+const FIFTH_POW: [u64; 10] = [
+ 0,
+ 1,
+ 2 * 2 * 2 * 2 * 2,
+ 3 * 3 * 3 * 3 * 3,
+ 4 * 4 * 4 * 4 * 4,
+ 5 * 5 * 5 * 5 * 5,
+ 6 * 6 * 6 * 6 * 6,
+ 7 * 7 * 7 * 7 * 7,
+ 8 * 8 * 8 * 8 * 8,
+ 9 * 9 * 9 * 9 * 9,
+];
+
+/// For n * 9 ^ 5 > 10^n - 1, max value of n is 5.
+fn method1() -> u64 {
+ const MAX: usize = 10;
+ let mut digits: [u8; MAX] = [0; MAX];
+ let mut fifth_power_nums = vec![];
+ // Skip 1
+ digits[0] = 1;
+ for i in 2..1_000_000_u64 {
+ let mut sum = 1;
+ for j in 0..MAX {
+ sum += digits[j];
+ if sum > 9 {
+ digits[j] = 0;
+ sum = 1;
+ } else {
+ digits[j] = sum;
+ break;
+ }
+ }
+
+ let sum: u64 = digits.iter().map(|digit| (*digit as u64).pow(5)).sum();
+ if sum == i {
+ fifth_power_nums.push(i);
+ }
+ }
+ fifth_power_nums.into_iter().sum()
+}
+
+fn method2() -> u64 {
+ let mut fifth_power_nums = vec![];
+ let mut s;
+ for i in 2..1_000_000_u64 {
+ s = i.to_string();
+ let sum: u64 = s
+ .bytes()
+ .map(|b| {
+ let digit: u64 = (b - b'0') as u64;
+ digit.pow(5)
+ })
+ .sum();
+ if sum == i {
+ fifth_power_nums.push(i);
+ }
+ }
+ fifth_power_nums.into_iter().sum()
+}
+
+fn method3() -> u64 {
+ const MAX: usize = 10;
+ let mut digits: [u8; MAX] = [0; MAX];
+ let mut fifth_power_nums = vec![];
+ digits[0] = 1;
+ for i in 2..1_000_000_u64 {
+ let mut sum = 1;
+ for j in 0..MAX {
+ sum += digits[j];
+ if sum > 9 {
+ digits[j] = 0;
+ sum = 1;
+ } else {
+ digits[j] = sum;
+ break;
+ }
+ }
+
+ let sum: u64 = digits.iter().map(|digit| FIFTH_POW[*digit as usize]).sum();
+ if sum == i {
+ fifth_power_nums.push(i);
+ }
+ }
+ fifth_power_nums.into_iter().sum()
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+ println!("method3: {}", method3());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 443839));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), 443839));
+}
+
+#[bench]
+fn bench_method3(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method3(), 443839));
+}
diff --git a/euler/rust/deprecated/bin/euler_031.rs b/euler/rust/deprecated/bin/euler_031.rs
new file mode 100644
index 00000000..03499c5e
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_031.rs
@@ -0,0 +1,129 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// In the United Kingdom the currency is made up of pound (£) and pence (p).
+/// There are eight coins in general circulation:
+/// 1p, 2p, 5p, 10p, 20p, 50p, £1 (100p), and £2 (200p).
+/// It is possible to make £2 in the following way:
+/// 1×£1 + 1×50p + 2×20p + 1×5p + 1×2p + 3×1p
+/// How many different ways can £2 be made using any number of coins?
+
+fn method1(max_num: usize) -> usize {
+ let mut count = 0;
+ for i200 in 0..=max_num {
+ let s200 = i200 * 200;
+ if s200 == max_num {
+ count += 1;
+ break;
+ }
+ if s200 > max_num {
+ break;
+ }
+ for i100 in 0..=max_num {
+ let s100 = s200 + i100 * 100;
+ if s100 == max_num {
+ count += 1;
+ break;
+ }
+ if s100 > max_num {
+ break;
+ }
+ for i50 in 0..=max_num {
+ let s50 = s100 + i50 * 50;
+ if s50 == max_num {
+ count += 1;
+ break;
+ }
+ if s50 > max_num {
+ break;
+ }
+
+ for i20 in 0..=max_num {
+ let s20 = s50 + i20 * 20;
+ if s20 == max_num {
+ count += 1;
+ break;
+ }
+ if s20 > max_num {
+ break;
+ }
+
+ for i10 in 0..=max_num {
+ let s10 = s20 + i10 * 10;
+ if s10 == max_num {
+ count += 1;
+ break;
+ }
+ if s10 > max_num {
+ break;
+ }
+ for i5 in 0..=max_num {
+ let s5 = s10 + i5 * 5;
+ if s5 == max_num {
+ count += 1;
+ break;
+ }
+ if s5 > max_num {
+ break;
+ }
+ for i2 in 0..=max_num {
+ let s2 = s5 + i2 * 2;
+ if s2 == max_num {
+ count += 1;
+ break;
+ }
+ if s2 < max_num {
+ //println!("s2: {}, i100:{}, i50: {}, i20: {}, i10: {}, i5: {}, i2: {}",s2, i100, i50, i20, i10, i5, i2);
+ count += 1;
+ } else if s2 == max_num {
+ //println!("s2: {}, i100:{}, i50: {}, i20: {}, i10: {}, i5: {}, i2: {}", s2, i100, i50, i20, i10, i5, i2);
+ count += 1;
+ break;
+ } else {
+ break;
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+
+ count
+}
+
+fn method2(max_num: usize) -> usize {
+ let coins = vec![1, 2, 5, 10, 20, 50, 100, 200];
+ let mut ways = vec![0; max_num + 1];
+ ways[0] = 1;
+ for coin in coins {
+ for j in coin..=max_num {
+ ways[j] += ways[j - coin];
+ }
+ }
+
+ ways[max_num]
+}
+
+fn main() {
+ let max_num = 200;
+ println!("ways: {}", method1(max_num));
+ println!("ways: {}", method2(max_num));
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(200), 73682));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(200), 73682));
+}
diff --git a/euler/rust/deprecated/bin/euler_032.rs b/euler/rust/deprecated/bin/euler_032.rs
new file mode 100644
index 00000000..c0f0cd9e
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_032.rs
@@ -0,0 +1,88 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use std::collections::HashSet;
+
+/// Problem:
+///
+/// We shall say that an n-digit number is pandigital if it makes use of
+/// all the digits 1 to n exactly once; for example, the 5-digit number, 15234,
+/// is 1 through 5 pandigital.
+///
+/// The product 7254 is unusual, as the identity, 39 × 186 = 7254,
+/// containing multiplicand, multiplier, and product is 1 through 9 pandigital.
+///
+/// Find the sum of all products whose multiplicand/multiplier/product identity
+/// can be written as a 1 through 9 pandigital.
+/// HINT: Some products can be obtained in more than one way so be sure
+/// to only include it once in your sum.
+
+fn method1() -> u32 {
+ let mut products: HashSet = HashSet::new();
+ let mut digits: [usize; 10] = [0; 10];
+ let mut is_pandigitals = |mut i: u32, mut j: u32, mut p: u32| -> bool {
+ if p > 9999 || p < 1000 {
+ return false;
+ }
+
+ for i in 0..digits.len() {
+ digits[i] = 0;
+ }
+
+ let mut r: usize;
+ let mut count = 0;
+ while i > 0 {
+ r = (i % 10) as usize;
+ if r == 0 || digits[r] != 0 {
+ return false;
+ }
+ digits[r] = r;
+ count += 1;
+ i /= 10;
+ }
+ while j > 0 {
+ r = (j % 10) as usize;
+ if r == 0 || digits[r] != 0 {
+ return false;
+ }
+ digits[r] = r;
+ count += 1;
+ j /= 10;
+ }
+ while p > 0 {
+ r = (p % 10) as usize;
+ if r == 0 || digits[r] != 0 {
+ return false;
+ }
+ digits[r] = r;
+ count += 1;
+ p /= 10;
+ }
+
+ count == 9
+ };
+
+ for i in 1..999 {
+ for j in i..9999 {
+ let p = i * j;
+ if is_pandigitals(i, j, p) {
+ products.insert(p);
+ }
+ }
+ }
+
+ products.into_iter().sum()
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 45228));
+}
diff --git a/euler/rust/deprecated/bin/euler_033.rs b/euler/rust/deprecated/bin/euler_033.rs
new file mode 100644
index 00000000..2e4a2815
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_033.rs
@@ -0,0 +1,59 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::gcd::Gcd;
+
+/// Problem:
+///
+/// The fraction 49/98 is a curious fraction, as an inexperienced mathematician
+/// in attempting to simplify it may incorrectly believe that 49/98 = 4/8,
+/// which is correct, is obtained by cancelling the 9s.
+///
+/// We shall consider fractions like, 30/50 = 3/5, to be trivial examples.
+///
+/// There are exactly four non-trivial examples of this type of fraction,
+/// less than one in value, and containing two digits in the numerator and
+/// denominator.
+///
+/// If the product of these four fractions is given in its lowest common terms,
+/// find the value of the denominator.
+
+fn method1() -> u32 {
+ let is_canceling_fraction = |numerator: u32, denominator: u32| -> bool {
+ let n1 = numerator / 10;
+ let n2 = numerator % 10;
+ let d1 = denominator / 10;
+ let d2 = denominator % 10;
+ (n2 == d1) && (n1 * denominator == d2 * numerator)
+ };
+
+ let mut denominators = 1;
+ let mut numerators = 1;
+ for i in 10..99_u32 {
+ for j in (i + 1)..=99 {
+ if is_canceling_fraction(i, j) {
+ println!("> {} / {}", i, j);
+ numerators *= i;
+ denominators *= j;
+ let common = u32::gcd(numerators, denominators);
+ numerators /= common;
+ denominators /= common;
+ }
+ }
+ }
+
+ denominators
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 100));
+}
diff --git a/euler/rust/deprecated/bin/euler_034.rs b/euler/rust/deprecated/bin/euler_034.rs
new file mode 100644
index 00000000..d20d8056
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_034.rs
@@ -0,0 +1,68 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::digits::GetDigits;
+
+/// Problem:
+///
+/// The Fibonacci sequence is defined by the recurrence relation:
+/// Fn = F_(n−1) + F_(n−2), where F1 = 1 and F2 = 1.
+/// Hence the first 12 terms will be:
+/// F1 = 1
+/// F2 = 1
+/// F3 = 2
+/// F4 = 3
+/// F5 = 5
+/// F6 = 8
+/// F7 = 13
+/// F8 = 21
+/// F9 = 34
+/// F10 = 55
+/// F11 = 89
+/// F12 = 144
+/// The 12th term, F12, is the first term to contain three digits.
+/// What is the index of the first term in the Fibonacci sequence to
+/// contain 1000 digits?
+
+/// f1(n) = 9! * n;
+/// f2(n) = 10^n - 1;
+/// 9_999_999 is upper bound.
+const UPPER_BOND: usize = 7;
+
+fn method1() -> u64 {
+ let mut product = 1;
+ let mut factorials: [u64; 10] = [1; 10];
+ for i in 1..=9 {
+ product *= i;
+ factorials[i] = product as u64;
+ }
+
+ let mut curious_nums = vec![];
+ let mut digits = Vec::with_capacity(UPPER_BOND);
+
+ for i in 1_u64..(UPPER_BOND as u64 * factorials[9]) {
+ digits.clear();
+ let _num_digits = i.get_digits(&mut digits);
+ let sum: u64 = digits.iter().map(|&digit| factorials[digit as usize]).sum();
+ if i == sum {
+ println!(">> {}", i);
+ curious_nums.push(i);
+ }
+ }
+
+ let s: u64 = curious_nums.into_iter().sum();
+ s - 1 - 2
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 40730));
+}
diff --git a/euler/rust/deprecated/bin/euler_035.rs b/euler/rust/deprecated/bin/euler_035.rs
new file mode 100644
index 00000000..4da49120
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_035.rs
@@ -0,0 +1,83 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate euler;
+extern crate test;
+
+use std::collections::HashSet;
+use std::iter::FromIterator;
+
+/// Problem:
+///
+/// The number, 197, is called a circular prime because all rotations of
+/// the digits: 197, 971, and 719, are themselves prime.
+/// There are thirteen such primes below 100:
+/// 2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, and 97.
+/// How many circular primes are there below one million?
+
+fn method1() -> u32 {
+ const MAX: usize = 1_000_000;
+ let mut circular_count = 0;
+ let prime_list = euler::primes::get_prime_list(MAX);
+ let primes: HashSet = HashSet::from_iter(prime_list.into_iter());
+ let is_circurlar_prime = |prime: usize| -> bool {
+ let rotate_digits = if prime > 100_000 {
+ 5
+ } else if prime > 10_000 {
+ 4
+ } else if prime > 1_000 {
+ 3
+ } else if prime > 100 {
+ 2
+ } else if prime > 10 {
+ 1
+ } else {
+ 0
+ };
+
+ let mut result = true;
+ let mut p = prime;
+ let rotate = 10_usize.pow(rotate_digits);
+ for _i in 0..rotate_digits {
+ let quotient = p / rotate;
+ // Skip prime numbers which contain even digits
+ if quotient == 0
+ || quotient == 2
+ || quotient == 4
+ || quotient == 5
+ || quotient == 6
+ || quotient == 8
+ {
+ result = false;
+ break;
+ }
+ // rotate left
+ p = p % rotate * 10 + quotient;
+ if !primes.contains(&p) {
+ result = false;
+ break;
+ }
+ }
+ result
+ };
+
+ for prime in &primes {
+ if is_circurlar_prime(*prime) {
+ //println!("> prime: {}", prime);
+ circular_count += 1;
+ }
+ }
+
+ circular_count
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 55));
+}
diff --git a/euler/rust/deprecated/bin/euler_036.rs b/euler/rust/deprecated/bin/euler_036.rs
new file mode 100644
index 00000000..b7df2c9a
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_036.rs
@@ -0,0 +1,125 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// The decimal number, 585 = 10010010012 (binary), is palindromic
+/// in both bases.
+///
+/// Find the sum of all numbers, less than one million, which are palindromic
+/// in base 10 and base 2.
+///
+/// (Please note that the palindromic number, in either base, may not
+/// include leading zeros.)
+
+fn is_palindrome(n: u32, base: u8) -> bool {
+ let s: String = if base == 10 {
+ n.to_string()
+ } else {
+ format!("{:b}", n)
+ };
+ let rev_s: String = s.chars().rev().collect();
+ s == rev_s
+}
+
+fn method1() -> u32 {
+ let mut palindromes: Vec = Vec::new();
+
+ for i in 1..1_000_000 {
+ if is_palindrome(i, 10) && is_palindrome(i, 2) {
+ palindromes.push(i);
+ }
+ }
+
+ palindromes.iter().sum()
+}
+
+fn is_palindrome2(num: u32, base: u32) -> bool {
+ let mut n = num;
+ let mut digits = vec![];
+ while n >= base {
+ digits.push(n % base);
+ n /= base;
+ }
+ digits.push(n);
+
+ let len = digits.len();
+ for i in 0..len {
+ if digits[i] != digits[len - i - 1] {
+ return false;
+ }
+ }
+
+ true
+}
+
+fn method2() -> u32 {
+ let mut palindromes: Vec = Vec::new();
+
+ for i in 1..1_000_000 {
+ if is_palindrome2(i, 10) && is_palindrome2(i, 2) {
+ palindromes.push(i);
+ }
+ }
+
+ palindromes.iter().sum()
+}
+
+fn method3() -> u32 {
+ // 1_000_000 consumes 20 bits in binary format.
+ let mut digits = Vec::with_capacity(20);
+ let mut is_palindrome3 = |num: u32, base: u32| -> bool {
+ let mut n = num;
+ digits.clear();
+
+ while n >= base {
+ digits.push(n % base);
+ n /= base;
+ }
+ digits.push(n);
+
+ let len = digits.len();
+ for i in 0..len {
+ if digits[i] != digits[len - i - 1] {
+ return false;
+ }
+ }
+
+ true
+ };
+
+ let mut palindromes: Vec = Vec::new();
+
+ for i in 1..1_000_000 {
+ if is_palindrome3(i, 10) && is_palindrome3(i, 2) {
+ palindromes.push(i);
+ }
+ }
+
+ palindromes.iter().sum()
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+ println!("method3: {}", method3());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 872187));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), 872187));
+}
+
+#[bench]
+fn bench_method3(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method3(), 872187));
+}
diff --git a/euler/rust/deprecated/bin/euler_037.rs b/euler/rust/deprecated/bin/euler_037.rs
new file mode 100644
index 00000000..f08961a2
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_037.rs
@@ -0,0 +1,66 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate euler;
+extern crate test;
+
+/// Problem:
+///
+/// The number 3797 has an interesting property. Being prime itself,
+/// it is possible to continuously remove digits from left to right,
+/// and remain prime at each stage: 3797, 797, 97, and 7.
+/// Similarly we can work from right to left: 3797, 379, 37, and 3.
+///
+/// Find the sum of the only eleven primes that are both truncatable from
+/// left to right and right to left.
+///
+/// NOTE: 2, 3, 5, and 7 are not considered to be truncatable primes.
+
+fn method1() -> usize {
+ let primes = euler::primes::get_prime_list(1_000_000);
+ let mut truncatable_primes: Vec = Vec::with_capacity(11);
+
+ let is_truncatable_prime = |prime: usize| -> bool {
+ let mut p = prime;
+ while p >= 10 {
+ p /= 10;
+ if primes.binary_search(&p).is_err() {
+ return false;
+ }
+ }
+ if primes.binary_search(&p).is_err() {
+ return false;
+ }
+
+ let mut base = 10;
+ let mut p;
+ while prime >= base {
+ p = prime % base;
+ base *= 10;
+ if primes.binary_search(&p).is_err() {
+ return false;
+ }
+ }
+
+ true
+ };
+
+ for prime in &primes {
+ if prime > &10 && is_truncatable_prime(*prime) {
+ println!("> #{}, {}", truncatable_primes.len() + 1, prime);
+ truncatable_primes.push(*prime);
+ }
+ }
+ truncatable_primes.iter().sum()
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 748317));
+}
diff --git a/euler/rust/deprecated/bin/euler_038.rs b/euler/rust/deprecated/bin/euler_038.rs
new file mode 100644
index 00000000..b7bb26e5
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_038.rs
@@ -0,0 +1,121 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// Take the number 192 and multiply it by each of 1, 2, and 3:
+///
+/// 192 × 1 = 192
+/// 192 × 2 = 384
+/// 192 × 3 = 576
+///
+/// By concatenating each product we get the 1 to 9 pandigital, 192384576.
+/// We will call 192384576 the concatenated product of 192 and (1,2,3)
+///
+/// The same can be achieved by starting with 9 and multiplying by 1, 2, 3, 4,
+/// and 5, giving the pandigital, 918273645, which is the concatenated product
+/// of 9 and (1,2,3,4,5).
+///
+/// What is the largest 1 to 9 pandigital 9-digit number that can be formed
+/// as the concatenated product of an integer with (1,2, ... , n) where n > 1?
+
+pub struct Pandigits {
+ digits: [bool; Self::MAX],
+ num: u64,
+}
+
+impl Pandigits {
+ const MAX: usize = 10;
+
+ pub fn new() -> Pandigits {
+ Pandigits {
+ digits: [false; Self::MAX],
+ num: 0,
+ }
+ }
+
+ pub fn reset(&mut self) {
+ for i in 0..Self::MAX {
+ self.digits[i] = false;
+ }
+ self.num = 0;
+ }
+
+ pub fn append(&mut self, orig_n: u64) -> bool {
+ let mut r: usize;
+ let mut n = orig_n;
+ let mut count = 0;
+ while n > 0 {
+ r = (n % 10) as usize;
+ n /= 10;
+ if r == 0 || self.digits[r] {
+ return false;
+ }
+ self.digits[r] = true;
+ count += 1;
+ }
+ self.num = self.num * 10_u64.pow(count) + orig_n;
+ true
+ }
+
+ pub fn is_pandigitals(&self) -> bool {
+ for i in 1..Self::MAX {
+ if !self.digits[i] {
+ return false;
+ }
+ }
+ true
+ }
+
+ pub fn get_num(&self) -> u64 {
+ self.num
+ }
+}
+
+fn method1() -> u64 {
+ let mut pandigits = Pandigits::new();
+ let mut max_pandigitals = 0;
+ let ranges = vec![
+ (2, 1000, 9999),
+ (3, 1000, 9999),
+ (4, 100, 999),
+ (5, 1, 99),
+ (6, 1, 9),
+ ];
+
+ for (n, start, end) in ranges.into_iter() {
+
+ 'i_range:
+ for i in start..end {
+ pandigits.reset();
+ for j in 1..=n {
+ if !pandigits.append(i * j) {
+ continue 'i_range;
+ }
+ }
+
+ if pandigits.is_pandigitals() {
+ let p = pandigits.get_num();
+ println!("> i: {}, p: {}, max: {}", i, p, max_pandigitals);
+ if p > max_pandigitals {
+ max_pandigitals = p;
+ }
+ }
+ }
+ }
+
+ max_pandigitals
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 932718654));
+}
diff --git a/euler/rust/deprecated/bin/euler_039.rs b/euler/rust/deprecated/bin/euler_039.rs
new file mode 100644
index 00000000..91a77e16
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_039.rs
@@ -0,0 +1,55 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// If p is the perimeter of a right angle triangle with integral length sides,
+/// {a,b,c}, there are exactly three solutions for p = 120.
+///
+/// {20,48,52}, {24,45,51}, {30,40,50}
+///
+/// For which value of p ≤ 1000, is the number of solutions maximised?
+
+fn method1() -> u32 {
+ let parse_triangle = |num: u32| {
+ let one_third = num / 3;
+ let half = num / 2;
+ let mut count = 0;
+
+ for a in 1..one_third {
+ for b in a..half {
+ let c = num - a - b;
+ if a * a + b * b == c * c {
+ count += 1;
+ }
+ }
+ }
+
+ count
+ };
+
+ let mut max_count = 0;
+ let mut max_num = 0;
+ for i in 120..=1000 {
+ let count = parse_triangle(i);
+ if count > max_count {
+ max_count = count;
+ max_num = i;
+ }
+ }
+
+ max_num
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 840));
+}
diff --git a/euler/rust/deprecated/bin/euler_040.rs b/euler/rust/deprecated/bin/euler_040.rs
new file mode 100644
index 00000000..340dfd54
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_040.rs
@@ -0,0 +1,81 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// An irrational decimal fraction is created by
+/// concatenating the positive integers:
+///
+/// 0.123456789101112131415161718192021...
+///
+/// It can be seen that the 12th digit of the fractional part is 1.
+///
+/// If dn represents the nth digit of the fractional part,
+/// find the value of the following expression.
+///
+/// d1 × d10 × d100 × d1000 × d10000 × d100000 × d1000000
+
+fn method1() -> u64 {
+ let mut result = String::with_capacity(1_000_000);
+ for i in 1..200_000 {
+ let s = i.to_string();
+ result += &s;
+ }
+
+ let mut product = 1;
+ for i in 0..6 {
+ let pos = 10_usize.pow(i) - 1;
+ product *= &result[pos..pos + 1].parse().unwrap();
+ }
+ product
+}
+
+fn method2() -> u64 {
+ const DIGITS: [u32; 6] = [9, 90 * 2, 900 * 3, 9000 * 4, 90_000 * 5, 900_000 * 6];
+
+ let get_digits = |num: u32| {
+ let mut n = num;
+ let mut i = 0;
+ let mut base = 1;
+ let mut num_digits = 1;
+ while n > DIGITS[i] {
+ n -= DIGITS[i];
+ i += 1;
+ base *= 10;
+ num_digits += 1;
+ }
+
+ let num_order = (n - 1) / num_digits + 1;
+ let digit_order = (n - 1) % num_digits;
+ let number = base + num_order - 1;
+ let s: String = number.to_string();
+ (s.bytes().nth(digit_order as usize).unwrap() - b'0') as u64
+ };
+
+ get_digits(1)
+ * get_digits(10)
+ * get_digits(100)
+ * get_digits(1000)
+ * get_digits(10_000)
+ * get_digits(100_000)
+ * get_digits(1_000_000)
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 210));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), 210));
+}
diff --git a/euler/rust/deprecated/bin/euler_041.rs b/euler/rust/deprecated/bin/euler_041.rs
new file mode 100644
index 00000000..53fd00cf
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_041.rs
@@ -0,0 +1,50 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::permutation::Permutation;
+use euler::primes::IsPrime;
+
+/// Problem:
+///
+/// We shall say that an n-digit number is pandigital if it makes use of
+/// all the digits 1 to n exactly once. For example, 2143 is a 4-digit
+/// pandigital and is also prime.
+///
+/// What is the largest n-digit pandigital prime that exists?
+
+fn method1() -> usize {
+ let mut largest_pandigital_prime = 0;
+
+ for i in 2..=7 {
+ let mut digits: Vec = vec![];
+ for j in 1..=i {
+ digits.push(j);
+ }
+ let p = Permutation::new(digits);
+ for d in p.into_iter() {
+ let mut num: usize = 0;
+ for digit in d {
+ num = num * 10 + digit as usize;
+ }
+ if num > largest_pandigital_prime && num.is_prime() {
+ println!("> {}, {}", num, largest_pandigital_prime);
+ largest_pandigital_prime = num;
+ }
+ }
+ }
+
+ largest_pandigital_prime
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 7652413));
+}
diff --git a/euler/rust/deprecated/bin/euler_042.rs b/euler/rust/deprecated/bin/euler_042.rs
new file mode 100644
index 00000000..c1b64b87
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_042.rs
@@ -0,0 +1,72 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use std::fs::File;
+use std::io::{BufRead, BufReader, Result};
+
+/// Problem:
+///
+
+/// The nth term of the sequence of triangle numbers is given by, t_n = ½n(n+1);
+/// so the first ten triangle numbers are:
+///
+/// 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
+///
+/// By converting each letter in a word to a number corresponding to
+/// its alphabetical position and adding these values we form a word value.
+/// For example, the word value for SKY is 19 + 11 + 25 = 55 = t10.
+/// If the word value is a triangle number then we shall call the word
+/// a triangle word.
+///
+/// Using words.txt (right click and 'Save Link/Target As...'), a 16K
+/// text file containing nearly two-thousand common English words,
+/// how many are triangle words?
+
+fn method1(words: &Vec>) -> usize {
+ let get_word_sum = |v: &Vec| -> u16 {
+ v.iter()
+ .map(|c| {
+ if c < &b'A' || c > &b'Z' {
+ 0
+ } else {
+ (c - b'A' + 1) as u16
+ }
+ })
+ .sum()
+ };
+
+ let triangle_nums: Vec = (1..100).map(|i| i * (i + 1) / 2).collect();
+ let is_triangle_num = |n: u16| -> bool { triangle_nums.binary_search(&n).is_ok() };
+
+ words
+ .iter()
+ .map(|word| get_word_sum(word))
+ .filter(|n| is_triangle_num(*n))
+ .count()
+}
+
+fn read_words(filepath: &str) -> Result>> {
+ let fd = File::open(filepath)?;
+ let buf = BufReader::new(fd);
+ Ok(buf.split(b',').map(|l| l.unwrap()).collect())
+}
+
+fn main() {
+ let filepath = if let Some(filepath) = std::env::args().nth(1) {
+ filepath
+ } else {
+ panic!("Usage: euler_042 words.txt");
+ };
+ let words = read_words(&filepath).unwrap();
+ println!("method1: {}", method1(&words));
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ let words = read_words("/etc/issue").unwrap();
+ b.iter(|| method1(&words));
+}
diff --git a/euler/rust/deprecated/bin/euler_043.rs b/euler/rust/deprecated/bin/euler_043.rs
new file mode 100644
index 00000000..0068cf33
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_043.rs
@@ -0,0 +1,69 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::permutation::Permutation;
+
+/// Problem:
+///
+/// The number, 1406357289, is a 0 to 9 pandigital number because it is
+/// made up of each of the digits 0 to 9 in some order, but it also
+/// has a rather interesting sub-string divisibility property.
+///
+/// Let d1 be the 1st digit, d2 be the 2nd digit, and so on. In this way,
+/// we note the following:
+///
+/// d2d3d4=406 is divisible by 2
+/// d3d4d5=063 is divisible by 3
+/// d4d5d6=635 is divisible by 5
+/// d5d6d7=357 is divisible by 7
+/// d6d7d8=572 is divisible by 11
+/// d7d8d9=728 is divisible by 13
+/// d8d9d10=289 is divisible by 17
+///
+/// Find the sum of all 0 to 9 pandigital numbers with this property.
+
+fn method1() -> u64 {
+ let mut sum = vec![];
+ let pairs = [
+ (1_usize, 2),
+ (2, 3),
+ (3, 5),
+ (4, 7),
+ (5, 11),
+ (6, 13),
+ (7, 17),
+ ];
+
+ let digits = vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+ let p = Permutation::new(digits);
+ 'iterator: for item in p.into_iter() {
+ for (i, prime) in &pairs {
+ let num = (item[*i] as u64) * 100 + (item[i + 1] as u64) * 10 + item[i + 2] as u64;
+ if num % prime != 0 {
+ continue 'iterator;
+ }
+ }
+
+ let mut num: u64 = 0;
+ for i in item {
+ num = (num * 10) + (i as u64);
+ }
+ println!("> {}", num);
+ sum.push(num);
+ }
+
+ sum.into_iter().sum()
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 16695334890));
+}
diff --git a/euler/rust/deprecated/bin/euler_044.rs b/euler/rust/deprecated/bin/euler_044.rs
new file mode 100644
index 00000000..1ad0097e
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_044.rs
@@ -0,0 +1,55 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// Pentagonal numbers are generated by the formula, Pn=n(3n−1)/2.
+/// The first ten pentagonal numbers are:
+///
+/// 1, 5, 12, 22, 35, 51, 70, 92, 117, 145, ...
+///
+/// It can be seen that P4 + P7 = 22 + 70 = 92 = P8. However, their difference,
+/// 70 − 22 = 48, is not pentagonal.
+///
+/// Find the pair of pentagonal numbers, Pj and Pk, for which their sum and
+/// difference are pentagonal and D = |Pk − Pj| is minimised;
+/// what is the value of D?
+
+fn method1() -> usize {
+ const MAX: usize = 2500;
+ let mut pentagons: [usize; MAX] = [0; MAX];
+ for i in 1..MAX {
+ let pentagon = i * (3 * i - 1) / 2;
+ pentagons[i] = pentagon;
+ }
+
+ let mut min_pentagon = pentagons[MAX - 1];
+ for i in 1..(MAX - 1) {
+ for j in (i + 1)..MAX {
+ let sum = pentagons[i] + pentagons[j];
+ let sub = pentagons[j] - pentagons[i];
+ if pentagons.binary_search(&sum).is_ok() && pentagons.binary_search(&sub).is_ok() {
+ println!("> i: {}, j: {}, sub: {}", i, j, sub);
+ if min_pentagon > sub {
+ min_pentagon = sub;
+ }
+ }
+ }
+ }
+
+ min_pentagon
+}
+
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 5482660));
+}
diff --git a/euler/rust/deprecated/bin/euler_045.rs b/euler/rust/deprecated/bin/euler_045.rs
new file mode 100644
index 00000000..4344bf95
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_045.rs
@@ -0,0 +1,61 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// Triangle, pentagonal, and hexagonal numbers are generated by the following
+/// formulae:
+///
+/// Triangle Tn=n(n+1)/2 1, 3, 6, 10, 15, ...
+/// Pentagonal Pn=n(3n−1)/2 1, 5, 12, 22, 35, ...
+/// Hexagonal Hn=n(2n−1) 1, 6, 15, 28, 45, ...
+///
+/// It can be verified that T285 = P165 = H143 = 40755.
+///
+/// Find the next triangle number that is also pentagonal and hexagonal.
+
+fn method1() -> u64 {
+ let mut i = 286;
+ let mut j = 166;
+ let mut k = 144;
+ loop {
+ let triangle = i * (i + 1) / 2;
+ let pentagonal = j * (3 * j - 1) / 2;
+ if triangle == pentagonal {
+ println!("> i: {}, j: {}, triangle: {}", i, j, triangle);
+ loop {
+ let hexagonal = k * (2 * k - 1);
+ if triangle == hexagonal {
+ println!("> i: {}, j: {}, k: {}", i, j, k);
+ println!(
+ ">> triangle: {}, pentagonal: {}, hexagonal: {}",
+ triangle, pentagonal, hexagonal
+ );
+ return triangle;
+ } else if triangle > hexagonal {
+ k += 1;
+ } else {
+ break;
+ }
+ }
+ i += 1;
+ } else if triangle > pentagonal {
+ j += 1;
+ } else if triangle < pentagonal {
+ i += 1;
+ }
+ }
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 1533776805));
+}
diff --git a/euler/rust/deprecated/bin/euler_046.rs b/euler/rust/deprecated/bin/euler_046.rs
new file mode 100644
index 00000000..0b2426d8
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_046.rs
@@ -0,0 +1,75 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::primes::get_prime_list;
+
+/// Problem:
+///
+/// It was proposed by Christian Goldbach that every odd composite number
+/// can be written as the sum of a prime and twice a square.
+///
+/// 9 = 7 + 2×1^2
+/// 15 = 7 + 2×2^2
+/// 21 = 3 + 2×3^2
+/// 25 = 7 + 2×3^2
+/// 27 = 19 + 2×2^2
+/// 33 = 31 + 2×1^2
+///kip
+/// It turns out that the conjecture was false.
+///
+/// What is the smallest odd composite that cannot be written as
+/// the sum of a prime and twice a square?
+
+fn method1() -> usize {
+ let primes = get_prime_list(100_000);
+ for num in (9..).step_by(2) {
+ if primes.binary_search(&num).is_ok() {
+ continue;
+ }
+
+ let mut ok = true;
+ for prime in &primes {
+ if prime > &num {
+ ok = false;
+ break;
+ }
+
+ ok = true;
+ let remainder = num - prime;
+ for i in 1.. {
+ let s = 2 * i * i;
+ if s > remainder {
+ ok = false;
+ break;
+ } else if s == remainder {
+ ok = true;
+ break;
+ }
+ }
+
+ if ok {
+ //println!("num: {}, prime: {}", num, prime);
+ break;
+ }
+ }
+
+ if !ok {
+ return num;
+ }
+ }
+
+ 0
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 5777));
+}
diff --git a/euler/rust/deprecated/bin/euler_047.rs b/euler/rust/deprecated/bin/euler_047.rs
new file mode 100644
index 00000000..b316a172
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_047.rs
@@ -0,0 +1,112 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate euler;
+extern crate test;
+
+/// Problem:
+///
+/// The first two consecutive numbers to have two distinct prime factors are:
+///
+/// 14 = 2 × 7
+/// 15 = 3 × 5
+///
+/// The first three consecutive numbers to have three distinct prime factors are:
+///
+/// 644 = 2² × 7 × 23
+/// 645 = 3 × 5 × 43
+/// 646 = 2 × 17 × 19.
+///
+/// Find the first four consecutive integers to have four distinct
+/// prime factors each. What is the first of these numbers?
+
+fn method1() -> usize {
+ let primes = euler::primes::get_prime_list(100_000);
+ let mut count = 0;
+ for i in 2.. {
+ let factors = euler::primes::get_prime_factors(i, &primes);
+ if factors.len() != 4 {
+ count = 0;
+ } else {
+ count += 1;
+ if count == 4 {
+ return i - 3;
+ }
+ }
+ }
+
+ 0
+}
+
+fn method2() -> usize {
+ let primes = euler::primes::get_prime_list(100_000);
+ let mut count = 0;
+ for i in 2.. {
+ let factors = euler::primes::get_prime_factor_num(i, &primes);
+ if factors != 4 {
+ count = 0;
+ } else {
+ count += 1;
+ if count == 4 {
+ return i - 3;
+ }
+ }
+ }
+
+ 0
+}
+
+fn method3() -> usize {
+ let primes = euler::primes::get_prime_list(100_000);
+ let mut i = 2;
+ loop {
+ let factors = euler::primes::get_prime_factor_num(i, &primes);
+ if factors != 4 {
+ i += 1;
+ continue;
+ }
+
+ let factors = euler::primes::get_prime_factor_num(i + 3, &primes);
+ if factors != 4 {
+ i += 4;
+ continue;
+ }
+
+ let factors = euler::primes::get_prime_factor_num(i + 2, &primes);
+ if factors != 4 {
+ i += 3;
+ continue;
+ }
+
+ let factors = euler::primes::get_prime_factor_num(i + 1, &primes);
+ if factors != 4 {
+ i += 2;
+ continue;
+ } else {
+ return i;
+ }
+ }
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+ println!("method3: {}", method3());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 134043));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), 134043));
+}
+
+#[bench]
+fn bench_method3(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method3(), 134043));
+}
diff --git a/euler/rust/deprecated/bin/euler_048.rs b/euler/rust/deprecated/bin/euler_048.rs
new file mode 100644
index 00000000..7093f4c5
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_048.rs
@@ -0,0 +1,60 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate num_bigint;
+extern crate test;
+
+use num_bigint::BigUint;
+use num_traits::pow::Pow;
+
+/// Problem:
+///
+/// The series, 1^1 + 2^2 + 3^3 + ... + 10^10 = 10405071317.
+///
+/// Find the last ten digits of the series, 1^1 + 2^2 + 3^3 + ... + 1000^1000.
+
+fn method1() -> String {
+ const MODULE: u64 = 10_000_000_000;
+ let mut sum: u64 = 0;
+ for i in 1..=1000 {
+ let mut product = 1;
+ for _j in 0..i {
+ product *= i;
+ product %= MODULE;
+ if product == 0 {
+ break;
+ }
+ }
+ sum += product;
+ }
+
+ let mut s = sum.to_string();
+ s.split_off(s.len() - 10)
+}
+
+fn method2() -> String {
+ let mut sum = BigUint::default();
+ for i in 1_u32..=1000 {
+ let num = BigUint::from(i).pow(i);
+ sum += num;
+ }
+ let mut s = sum.to_string();
+ s.split_off(s.len() - 10)
+}
+
+fn main() {
+ println!("last 10 digits: {}", method1());
+ println!("last 10 digits: {}", method2());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), "9110846700"));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), "9110846700"));
+}
diff --git a/euler/rust/deprecated/bin/euler_049.rs b/euler/rust/deprecated/bin/euler_049.rs
new file mode 100644
index 00000000..2474756a
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_049.rs
@@ -0,0 +1,78 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::permutation::Permutation;
+use euler::primes::get_prime_list;
+
+/// Problem:
+///
+/// The arithmetic sequence, 1487, 4817, 8147, in which each of the terms
+/// increases by 3330, is unusual in two ways: (i) each of the three terms
+/// are prime, and, (ii) each of the 4-digit numbers are permutations of
+/// one another.
+///
+/// There are no arithmetic sequences made up of three 1-, 2-, or
+/// 3-digit primes, exhibiting this property, but there is one other 4-digit
+/// increasing sequence.
+///
+/// What 12-digit number do you form by concatenating the three terms in
+/// this sequence?
+
+fn method1() -> Option<(usize, usize, usize)> {
+ let primes = get_prime_list(10000);
+ let get_digits = |mut num: usize| -> Vec {
+ let mut v = vec![];
+ while num > 0 {
+ v.push(num % 10);
+ num /= 10;
+ }
+ v
+ };
+
+ for prime in &primes {
+ if prime < &1000 {
+ continue;
+ }
+
+ let mut nums = vec![*prime];
+ let p = Permutation::new(get_digits(*prime));
+ for digits in p.into_iter() {
+ let n = digits.iter().fold(0, |prod, i| prod * 10 + i);
+ if n > 1000 && &n > prime && primes.binary_search(&n).is_ok() {
+ nums.push(n);
+ }
+ }
+ nums.sort();
+ nums.dedup();
+ if nums.len() < 3 {
+ continue;
+ }
+
+ // combinations
+ let len = nums.len();
+ for i in 0..len - 2 {
+ for j in i + 1..len - 1 {
+ for k in j + 1..len {
+ if nums[j] - nums[i] == nums[k] - nums[j] && nums[i] != 1487 {
+ return Some((nums[i], nums[j], nums[k]));
+ }
+ }
+ }
+ }
+ }
+
+ None
+}
+
+fn main() {
+ println!("method1: {:?}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), Some((2969, 6299, 9629))));
+}
diff --git a/euler/rust/deprecated/bin/euler_050.rs b/euler/rust/deprecated/bin/euler_050.rs
new file mode 100644
index 00000000..e930f2f2
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_050.rs
@@ -0,0 +1,59 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// The prime 41, can be written as the sum of six consecutive primes:
+/// 41 = 2 + 3 + 5 + 7 + 11 + 13
+///
+/// This is the longest sum of consecutive primes that adds to a prime
+/// below one-hundred.
+///
+/// The longest sum of consecutive primes below one-thousand that adds to
+/// a prime, contains 21 terms, and is equal to 953.
+///
+/// Which prime, below one-million, can be written as the sum
+/// of the most consecutive primes?
+
+fn method1() -> usize {
+ const MAX: usize = 1_000_000;
+ let primes = euler::primes::get_prime_list(MAX);
+ let len = primes.len();
+ let mut max_consecutive_prime = 0;
+ let mut max_consecutive_count = 0;
+ for i in 0..len {
+ let prime = primes[i];
+ for j in 0..i {
+ let mut count = 0;
+ let mut sum = 0;
+ while sum < prime && j + count < i {
+ sum += primes[j + count];
+ count += 1;
+ }
+ if count <= max_consecutive_count {
+ break;
+ }
+ if sum == prime {
+ if count > max_consecutive_count {
+ max_consecutive_prime = prime;
+ max_consecutive_count = count;
+ }
+ break;
+ }
+ }
+ }
+ max_consecutive_prime
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 997651));
+}
diff --git a/euler/rust/deprecated/bin/euler_052.rs b/euler/rust/deprecated/bin/euler_052.rs
new file mode 100644
index 00000000..f89def06
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_052.rs
@@ -0,0 +1,98 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// It can be seen that the number, 125874, and its double, 251748,
+/// contain exactly the same digits, but in a different order.
+///
+/// Find the smallest positive integer, x, such that 2x, 3x, 4x, 5x, and 6x,
+/// contain the same digits.
+
+fn method1() -> u32 {
+ let get_digits = |num: u32| {
+ let mut n = num;
+ let mut digits: [u8; 8] = [0; 8];
+ let mut i = 0;
+ while n > 9 {
+ digits[i] = (n % 10) as u8;
+ i += 1;
+ n /= 10;
+ }
+ digits[i] = n as u8;
+ digits.sort();
+ digits
+ };
+
+ for i in 100.. {
+ let digits = get_digits(i);
+ if digits == get_digits(i * 2)
+ && digits == get_digits(i * 3)
+ && digits == get_digits(i * 4)
+ && digits == get_digits(i * 5)
+ && digits == get_digits(i * 6)
+ {
+ return i;
+ }
+ }
+ 0
+}
+
+fn method2() -> u32 {
+ let get_digits = |num: u32| {
+ let mut n = num;
+ let mut digits: [u8; 8] = [0; 8];
+ let mut i = 0;
+ while n > 9 {
+ digits[i] = (n % 10) as u8;
+ i += 1;
+ n /= 10;
+ }
+ digits[i] = n as u8;
+ digits.sort();
+ digits
+ };
+
+ let get_base = |num: u32| {
+ let mut n = num;
+ let mut base = 1;
+ while n > 9 {
+ n /= 10;
+ base += 1;
+ }
+ base
+ };
+
+ for i in 100.. {
+ let num = i + 10_u32.pow(get_base(i));
+ let digits = get_digits(num);
+ if digits == get_digits(num * 2)
+ && digits == get_digits(num * 3)
+ && digits == get_digits(num * 4)
+ && digits == get_digits(num * 5)
+ && digits == get_digits(num * 6)
+ {
+ return num;
+ }
+ }
+ 0
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 142857));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), 142857));
+}
diff --git a/euler/rust/deprecated/bin/euler_053.rs b/euler/rust/deprecated/bin/euler_053.rs
new file mode 100644
index 00000000..6075379b
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_053.rs
@@ -0,0 +1,51 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use num_bigint::BigUint;
+use std::ops::Div;
+
+/// Problem:
+///
+/// There are exactly ten ways of selecting three from five, 12345:
+/// 123, 124, 125, 134, 135, 145, 234, 235, 245, and 345
+///
+/// In combinatorics, we use the notation, (5/3)=10.
+///
+/// In general, (n/r)=n!/ (r!(n−r)!) , where r≤n, n!=n×(n−1)×...×3×2×1, and 0!=1 .
+///
+/// It is not until n=23, that a value exceeds one-million: (23/10)=1144066.
+///
+/// How many, not necessarily distinct, values of (n/r) for 1≤n≤100,
+/// are greater than one-million?
+
+fn combination(n: u32, r: u32) -> BigUint {
+ let p1 = ((r + 1)..=n).fold(BigUint::from(1_u32), |prod, i| prod * i);
+ let p2 = (1..=(n - r)).fold(BigUint::from(1_u32), |prod, i| prod * i);
+ p1.div(p2)
+}
+
+fn method1() -> u32 {
+ let mut count = 0;
+ let threshold = BigUint::from(1_000_000_u32);
+ for i in 1..=100 {
+ for j in 1..=i {
+ if combination(i, j) > threshold {
+ count += 1;
+ }
+ }
+ }
+ count
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 4075));
+}
diff --git a/euler/rust/deprecated/bin/euler_056.rs b/euler/rust/deprecated/bin/euler_056.rs
new file mode 100644
index 00000000..4781ca52
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_056.rs
@@ -0,0 +1,45 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use num_bigint::BigUint;
+use num_traits::pow::Pow;
+
+/// Problem:
+///
+/// A googol (10100) is a massive number: one followed by one-hundred zeros;
+/// 100100 is almost unimaginably large: one followed by two-hundred zeros.
+/// Despite their size, the sum of the digits in each number is only 1.
+///
+/// Considering natural numbers of the form, ab, where a, b < 100,
+/// what is the maximum digital sum?
+
+fn method1() -> u32 {
+ let mut largest_sum = 0;
+ for i in 2..100_u16 {
+ for j in 2..100_u16 {
+ let p: BigUint = BigUint::from(i).pow(j);
+ let len = p
+ .to_radix_le(10)
+ .iter()
+ .map(|num: &u8| -> u32 { *num as u32 })
+ .sum();
+ if len > largest_sum {
+ largest_sum = len;
+ }
+ }
+ }
+ largest_sum
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 972));
+}
diff --git a/euler/rust/deprecated/bin/euler_057.rs b/euler/rust/deprecated/bin/euler_057.rs
new file mode 100644
index 00000000..7f824b1b
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_057.rs
@@ -0,0 +1,55 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use num_bigint::BigUint;
+
+/// Problem:
+///
+/// It is possible to show that the square root of two can be expressed as
+/// an infinite continued fraction.
+///
+/// √2 = 1 + 1/(2+1/(2+1/2+…))
+///
+/// By expanding this for the first four iterations, we get:
+///
+/// 1+1/2 = 3/2 = 1.5
+/// 1+1/(2+1/2) = 7/5 = 1.4
+/// 1+1/(2+1/(2+1/2)) = 17/12 = 1.41666…
+/// 1+1/(2+1/(2+1(2+1/2))) = 41/29 = 1.41379…
+///
+///
+/// The next three expansions are 99/70, 239/169, and 577/408, but the eighth
+/// expansion, 1393/985, is the first example where the number of digits
+/// in the numerator exceeds the number of digits in the denominator.
+///
+/// In the first one-thousand expansions, how many fractions contain
+/// a numerator with more digits than the denominator?
+
+fn method1() -> u32 {
+ let mut count = 0;
+ let mut numerator = BigUint::from(3_u32);
+ let mut denominator = BigUint::from(2_u32);
+ let mut tmp;
+ for _i in 1..1000 {
+ if numerator.to_string().len() > denominator.to_string().len() {
+ count += 1;
+ }
+ tmp = denominator.clone();
+ denominator += &numerator;
+ numerator += tmp * 2_u32;
+ }
+ count
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 153));
+}
diff --git a/euler/rust/deprecated/bin/euler_060.rs b/euler/rust/deprecated/bin/euler_060.rs
new file mode 100644
index 00000000..35490831
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_060.rs
@@ -0,0 +1,105 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::concate_number::ConcateNumber;
+use euler::primes::{get_prime_list, IsPrime};
+use std::collections::BTreeMap;
+
+/// Problem:
+///
+/// The primes 3, 7, 109, and 673, are quite remarkable. By taking any
+/// two primes and concatenating them in any order the result will always
+/// be prime. For example, taking 7 and 109, both 7109 and 1097 are prime.
+/// The sum of these four primes, 792, represents the lowest sum for a set
+/// of four primes with this property.
+///
+/// Find the lowest sum for a set of five primes for which any two primes
+/// concatenate to produce another prime.
+
+fn method1() -> usize {
+ const MAX: usize = 10_000;
+ let primes = get_prime_list(MAX);
+
+ let is_prime = |num: usize| -> bool { primes.binary_search(&num).is_ok() };
+
+ type PrimePair = Vec;
+ let mut prime_maps: BTreeMap = BTreeMap::new();
+
+ for p1 in &primes {
+ let mut prime_pair = PrimePair::new();
+ for p2 in &primes {
+ if p1 < p2 {
+ let c1 = p1.concate(*p2);
+ let c2 = p2.concate(*p1);
+ if c1 > MAX || c2 > MAX {
+ if c1.is_prime() && c2.is_prime() {
+ prime_pair.push(*p2);
+ }
+ } else {
+ if is_prime(c1) && is_prime(c2) {
+ prime_pair.push(*p2);
+ }
+ }
+ }
+ }
+
+ if prime_pair.len() > 3 {
+ prime_maps.insert(*p1, prime_pair);
+ }
+ }
+
+ // TODO(Shaohua): Replace with combination
+ for (p0, pair0) in prime_maps.iter() {
+ for p1 in pair0 {
+ if let Some(pair1) = prime_maps.get(&p1) {
+ for p2 in pair1 {
+ if !pair0.contains(p2) {
+ continue;
+ }
+ if let Some(pair2) = prime_maps.get(&p2) {
+ for p3 in pair2 {
+ if !pair0.contains(p3) {
+ continue;
+ }
+ if !pair1.contains(p3) {
+ continue;
+ }
+ println!("{}, {}, {}, {}", p0, p1, p2, p3);
+
+ if let Some(pair3) = prime_maps.get(&p3) {
+ for p4 in pair3 {
+ if !pair0.contains(p4) {
+ continue;
+ }
+ if !pair1.contains(p4) {
+ continue;
+ }
+ if !pair2.contains(p4) {
+ continue;
+ }
+ println!("{}, {}, {}, {}, {}", p0, p1, p2, p3, p4);
+ return p0 + p1 + p2 + p3 + p4;
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+
+ 0
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 26033));
+}
diff --git a/euler/rust/deprecated/bin/euler_063.rs b/euler/rust/deprecated/bin/euler_063.rs
new file mode 100644
index 00000000..e186caf8
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_063.rs
@@ -0,0 +1,42 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+use euler::digits::CountDigits;
+
+/// Problem:
+///
+/// The 5-digit number, 16807=7^5, is also a fifth power. Similarly,
+/// the 9-digit number, 134217728=8^9, is a ninth power.
+///
+/// How many n-digit positive integers exist which are also an nth power?
+
+fn method1() -> u32 {
+ let mut count = 0;
+ // Obveriously root number cannot be larger than 10
+ for i in 1..10_u128 {
+ for j in 1_u32.. {
+ let p = i.pow(j);
+ let n_digits = p.count_digits() as u32;
+ if j == n_digits {
+ println!("{} = {}^{}", p, i, j);
+ count += 1;
+ } else if j > n_digits {
+ break;
+ }
+ }
+ }
+ count
+}
+
+fn main() {
+ println!("method1: {}", method1());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 49));
+}
diff --git a/euler/rust/deprecated/bin/euler_092.rs b/euler/rust/deprecated/bin/euler_092.rs
new file mode 100644
index 00000000..4471d4fb
--- /dev/null
+++ b/euler/rust/deprecated/bin/euler_092.rs
@@ -0,0 +1,87 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// A number chain is created by continuously adding the square of the digits
+/// in a number to form a new number until it has been seen before.
+///
+/// For example,
+///
+/// 44 → 32 → 13 → 10 → 1 → 1
+/// 85 → 89 → 145 → 42 → 20 → 4 → 16 → 37 → 58 → 89
+///
+/// Therefore any chain that arrives at 1 or 89 will become stuck in an
+/// endless loop. What is most amazing is that EVERY starting number will
+/// eventually arrive at 1 or 89.
+///
+/// How many starting numbers below ten million will arrive at 89?
+
+fn method1() -> u64 {
+ let mut count = 0;
+ for i in 1..10_000_000_u32 {
+ let mut s = get_square_digit(i);
+ while s != 89 && s != 1 {
+ s = get_square_digit(s);
+ }
+ if s == 89 {
+ count += 1;
+ }
+ }
+
+ count
+}
+
+fn get_square_digit(mut num: u32) -> u32 {
+ let mut r;
+ let mut sum = 0;
+ while num >= 10 {
+ r = num % 10;
+ num /= 10;
+ sum += r * r;
+ }
+ sum + num * num
+}
+
+fn method2() -> u64 {
+ let mut cache: [bool; 1000] = [false; 1000];
+
+ let mut count = 0;
+ for i in 1..10_000_000_u32 {
+ let mut s = get_square_digit(i);
+ while s != 89 && s != 1 {
+ if cache[s as usize] {
+ s = 89;
+ break;
+ }
+ s = get_square_digit(s);
+ }
+ if s == 89 {
+ count += 1;
+ if i < 1000 {
+ cache[i as usize] = true;
+ }
+ }
+ }
+
+ count
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 8581146));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), 8581146));
+}
diff --git a/euler/rust/deprecated/bin/todo.md b/euler/rust/deprecated/bin/todo.md
new file mode 100644
index 00000000..9b9749b9
--- /dev/null
+++ b/euler/rust/deprecated/bin/todo.md
@@ -0,0 +1,8 @@
+
+## graph
+- [ ] 015
+- [ ] 018
+- [ ] 067
+
+## permutation
+- [ ] 24
diff --git a/euler/rust/deprecated/concate_number.rs b/euler/rust/deprecated/concate_number.rs
new file mode 100644
index 00000000..9f80cfc9
--- /dev/null
+++ b/euler/rust/deprecated/concate_number.rs
@@ -0,0 +1,38 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+pub trait ConcateNumber {
+ fn concate(&self, other: Self) -> Self;
+}
+
+macro_rules! concate_number_impl {
+ ( $( $t:ident )* ) => {
+ $(
+ impl ConcateNumber for $t {
+ fn concate(&self, other: Self) -> Self {
+ let mut shift = 1;
+ let mut q = other;
+ while q >= 10 {
+ q /= 10;
+ shift += 1;
+ }
+ self * (10 as $t).pow(shift) + other
+ }
+ }
+ )*
+ };
+}
+
+concate_number_impl!(u8 u16 u32 usize u64 u128);
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn test_concate_number() {
+ assert_eq!(12_u32.concate(42), 1242);
+ assert_eq!(42_u64.concate(10), 4210);
+ }
+}
diff --git a/euler/rust/deprecated/digits.rs b/euler/rust/deprecated/digits.rs
new file mode 100644
index 00000000..a1ddf4d5
--- /dev/null
+++ b/euler/rust/deprecated/digits.rs
@@ -0,0 +1,51 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+pub trait CountDigits {
+ fn count_digits(&self) -> u16;
+}
+
+macro_rules! count_digits_impl {
+ ( $( $t:ident )* ) => {
+ $(
+ impl CountDigits for $t {
+ fn count_digits(&self) -> u16 {
+ let mut count = 1;
+ let mut n = *self;
+ while n >= 10 {
+ count += 1;
+ n /= 10;
+ }
+ count
+ }
+ }
+ )*
+ };
+}
+
+count_digits_impl!(u8 u16 u32 u64 u128);
+
+pub trait GetDigits {
+ fn get_digits(&self, buf: &mut Vec) -> usize;
+}
+
+macro_rules! get_digits_impl {
+ ( $( $t:ident )* ) => {
+ $(
+ impl GetDigits for $t {
+ fn get_digits(&self, buf: &mut Vec) -> usize {
+ let mut n = *self;
+ let old_len = buf.len();
+ while n > 0 {
+ buf.push((n % 10) as u8);
+ n /= 10;
+ }
+ buf.len() - old_len
+ }
+ }
+ )*
+ };
+}
+
+get_digits_impl!(u8 u16 u32 u64 u128);
diff --git a/euler/rust/deprecated/gcd.rs b/euler/rust/deprecated/gcd.rs
new file mode 100644
index 00000000..a0d7791a
--- /dev/null
+++ b/euler/rust/deprecated/gcd.rs
@@ -0,0 +1,80 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+pub trait Gcd {
+ type Output;
+ fn gcd(self, denominator: Denominator) -> Self::Output;
+}
+
+macro_rules! gcd_impl {
+ ( $( $t:ident )* ) => {
+ $(
+ impl Gcd for $t {
+ type Output = $t;
+
+ /// Implemented based on the Euclidean Algorithm
+ fn gcd(self, denominator: $t) -> $t {
+ assert!(self > 0);
+ assert!(denominator > 0);
+ let (mut n, mut d) = if self > denominator {
+ (self, denominator)
+ } else {
+ (denominator, self)
+ };
+
+ while d != 0 {
+ let r = n % d;
+ n = d;
+ d = r;
+ }
+
+ n
+ }
+ }
+ )*
+ };
+}
+
+gcd_impl!(u8 i8 u16 i16 u32 i32 usize isize u64 i64 u128 i128);
+
+pub trait Lcm {
+ type Output;
+ fn lcm(self, denominator: Denominator) -> Self::Output;
+}
+
+macro_rules! lcm_impl {
+ ( $( $t:ident )* ) => {
+ $(
+ impl Lcm for $t {
+ type Output = $t;
+
+ /// Based on the theorem: `a * b = gcd(a, b) * lcm(a, b)`
+ fn lcm(self, denominator: $t) -> $t {
+ let gcd = self.gcd(denominator);
+ self / gcd * denominator
+ }
+ }
+ )*
+ };
+}
+
+lcm_impl!(u8 i8 u16 i16 u32 i32 usize isize u64 i64 u128 i128);
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn test_gcd() {
+ assert_eq!(i8::gcd(8, 16), 8);
+ assert_eq!(u64::gcd(42, 21), 21);
+ }
+
+ #[test]
+ fn test_lcm() {
+ assert_eq!(i8::lcm(8, 16), 16);
+ assert_eq!(u64::lcm(42, 21), 42);
+ assert_eq!(u64::lcm(42, 21), 42);
+ }
+}
diff --git a/euler/rust/deprecated/lib.rs b/euler/rust/deprecated/lib.rs
new file mode 100644
index 00000000..012efe2c
--- /dev/null
+++ b/euler/rust/deprecated/lib.rs
@@ -0,0 +1,9 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+pub mod concate_number;
+pub mod digits;
+pub mod gcd;
+pub mod permutation;
+pub mod primes;
diff --git a/euler/rust/deprecated/permutation.rs b/euler/rust/deprecated/permutation.rs
new file mode 100644
index 00000000..e0ca8d3f
--- /dev/null
+++ b/euler/rust/deprecated/permutation.rs
@@ -0,0 +1,112 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+//! Heap's algorithms to generate all possible permutations of n objects.
+//! See: https://en.wikipedia.org/wiki/Heap%27s_algorithm
+
+#[derive(Clone, Debug)]
+pub struct Permutation {
+ data: Vec,
+ swaps: Vec,
+ index: usize,
+}
+
+impl Permutation {
+ pub fn new(data: Vec) -> Permutation {
+ let len = data.len();
+ Permutation {
+ data,
+ swaps: vec![0; len],
+ index: 0,
+ }
+ }
+}
+
+// TODO(Shaohua): Returns references only.
+impl Iterator for Permutation {
+ type Item = Vec;
+
+ fn next(&mut self) -> Option {
+ if self.index > 0 {
+ loop {
+ if self.index >= self.swaps.len() {
+ return None;
+ }
+ if self.swaps[self.index] < self.index {
+ break;
+ }
+ self.swaps[self.index] = 0;
+ self.index += 1;
+ }
+
+ let pos = (self.index & 1) * self.swaps[self.index];
+ self.data.swap(self.index, pos);
+ self.swaps[self.index] += 1;
+ }
+ self.index = 1;
+ Some(self.data.clone())
+ }
+}
+
+#[derive(Debug)]
+pub struct Combination {
+ chunk_len: u32,
+ min: u32,
+ mask: u32,
+ data: Vec,
+}
+
+impl Combination {
+ pub fn new(chunk_len: u32, data: Vec) -> Self {
+ let len = data.len() as u32;
+ let min = 2_u32.pow(chunk_len) - 1;
+ // FIXME(Shaohua): multiply overflow for large vectors.
+ let max = 2_u32.pow(len) - 2_u32.pow(len - chunk_len);
+
+ Combination {
+ chunk_len,
+ min: min as u32,
+ mask: max as u32,
+ data,
+ }
+ }
+
+ fn get_chunk(&self) -> Vec {
+ let b = format!("{:01$b}", self.mask, self.data.len());
+ b.chars()
+ .enumerate()
+ .filter(|&(_, e)| e == '1')
+ .map(|(i, _)| self.data[i].clone())
+ .collect()
+ }
+}
+
+// TODO(Shaohua): Returns reference.
+impl Iterator for Combination {
+ type Item = Vec;
+
+ fn next(&mut self) -> Option {
+ while self.mask >= self.min {
+ if self.mask.count_ones() == self.chunk_len {
+ let res = self.get_chunk();
+ self.mask -= 1;
+ return Some(res);
+ }
+ self.mask -= 1;
+ }
+ None
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::Permutation;
+
+ #[test]
+ fn test_permutation() {
+ let arr = vec![1, 2, 3, 5, 8];
+ let p = Permutation::new(arr);
+ assert_eq!(p.into_iter().count(), 120);
+ }
+}
diff --git a/euler/rust/deprecated/primes.rs b/euler/rust/deprecated/primes.rs
new file mode 100644
index 00000000..e68f11a9
--- /dev/null
+++ b/euler/rust/deprecated/primes.rs
@@ -0,0 +1,181 @@
+pub fn get_prime_list(max_num: usize) -> Vec {
+ let mut list = vec![true; max_num + 1];
+ let sqrt = (max_num as f64).sqrt() as usize;
+ let mut mul;
+ for i in 2..(sqrt + 2) {
+ for j in 2..max_num {
+ mul = i * j;
+ if mul > max_num {
+ break;
+ }
+ list[mul] = false;
+ }
+ }
+
+ let mut result = vec![];
+ for i in 2..max_num {
+ if list[i] {
+ result.push(i);
+ }
+ }
+
+ result
+}
+
+pub trait IsPrime {
+ fn is_prime(&self) -> bool;
+}
+
+macro_rules! is_prime_impl {
+ ( $( $t:ident )* ) => {
+ $(
+ impl IsPrime for $t {
+ fn is_prime(&self) -> bool {
+ if self <= &0 {
+ return false;
+ }
+ if self % 2 == 0 {
+ return false;
+ }
+
+ let mut d = 3;
+ while &(d * d) <= self {
+ if self % d == 0 {
+ return false;
+ }
+ d += 2;
+ }
+ return true;
+ }
+ }
+ )*
+ };
+}
+
+is_prime_impl!(u8 i8 u16 i16 u32 i32 usize isize u64 i64 u128 i128);
+
+#[derive(Debug, Clone, Copy)]
+pub struct PrimeFactor {
+ pub num: usize,
+ pub count: u16,
+}
+
+pub fn get_prime_factors(num: usize, primes: &[usize]) -> Vec {
+ let mut result = Vec::::new();
+ let mut rem = num;
+ let root = (num as f64).sqrt().ceil() as usize;
+ for p in primes {
+ if rem == 1 {
+ break;
+ }
+ if p > &root {
+ if rem > 1 {
+ result.push(PrimeFactor { num: rem, count: 1 });
+ }
+ break;
+ }
+ let mut prime_factor = PrimeFactor { num: *p, count: 0 };
+ while rem != 1 {
+ if rem % *p == 0 {
+ prime_factor.count += 1;
+ rem /= *p;
+ } else {
+ break;
+ }
+ }
+ if prime_factor.count > 0 {
+ result.push(prime_factor);
+ }
+ }
+
+ result
+}
+
+pub trait GetFactors {
+ type Output;
+ fn get_factors(self) -> Self::Output;
+ fn get_factors_cache(self, v: &mut Self::Output);
+}
+
+macro_rules! get_factors_impl {
+ ( $( $t:ident )* ) => {
+ $(
+ impl GetFactors for $t {
+ type Output = Vec<$t>;
+ fn get_factors(self) -> Self::Output {
+ let mut factors = Vec::new();
+ if self <= 0 {
+ return factors;
+ }
+ for i in 1..self {
+ if self % i == 0 {
+ factors.push(i);
+ }
+ }
+ return factors;
+ }
+
+ fn get_factors_cache(self, v: &mut Self::Output) {
+ v.clear();
+ if self <= 0 {
+ return;
+ }
+ for i in 1..self {
+ if self % i == 0 {
+ v.push(i);
+ }
+ }
+ }
+ }
+ )*
+ };
+}
+get_factors_impl!(u8 i8 u16 i16 u32 i32 usize isize u64 i64 u128 i128);
+
+pub fn get_prime_factor_num(num: usize, primes: &[usize]) -> u32 {
+ let mut count = 0;
+ let mut rem = num;
+ let root = (num as f64).sqrt().ceil() as usize;
+ for p in primes {
+ if rem == 1 {
+ break;
+ }
+ if p > &root {
+ if rem > 1 {
+ count += 1;
+ }
+ break;
+ }
+ let mut is_factor = false;
+ while rem != 1 {
+ if rem % *p == 0 {
+ rem /= *p;
+ is_factor = true;
+ } else {
+ break;
+ }
+ }
+ if is_factor {
+ count += 1;
+ }
+ }
+
+ count
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn test_get_factors() {
+ let factors = 12_u32.get_factors();
+ assert_eq!(factors, vec![1, 2, 3, 4, 6]);
+ }
+
+ #[test]
+ fn test_is_prime() {
+ assert!(31_u32.is_prime());
+ assert!(!64_u16.is_prime());
+ }
+}
diff --git a/euler/rust/euler-001/Cargo.toml b/euler/rust/euler-001/Cargo.toml
new file mode 100644
index 00000000..2a7345de
--- /dev/null
+++ b/euler/rust/euler-001/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "euler-001"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/euler/rust/euler-001/src/main.rs b/euler/rust/euler-001/src/main.rs
new file mode 100644
index 00000000..399741e4
--- /dev/null
+++ b/euler/rust/euler-001/src/main.rs
@@ -0,0 +1,108 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// If we list all the natural numbers below 10 that are multiples of 3 or 5,
+/// we get 3, 5, 6 and 9. The sum of these multiples is 23.
+///
+/// Find the sum of all the multiples of 3 or 5 below 1000.
+
+fn method1(max_num: usize) -> usize {
+ let mut arr = vec![false; max_num + 1];
+ for i in 1..max_num {
+ let mul = i * 3;
+ if mul > max_num {
+ break;
+ }
+ arr[mul] = true;
+ }
+
+ for i in 1..max_num {
+ let mul = i * 5;
+ if mul > max_num {
+ break;
+ }
+ arr[mul] = true;
+ }
+
+ let mut sum = 0;
+ for (i, item) in arr.iter().enumerate().take(max_num).skip(1) {
+ if *item {
+ sum += i;
+ }
+ }
+ sum
+}
+
+fn method2(max_num: usize) -> usize {
+ let mut sum = 0;
+ for i in 1..max_num {
+ let mul = i * 3;
+ if mul >= max_num {
+ break;
+ }
+ sum += mul;
+ }
+
+ let mut reminder = 0;
+ for i in 1..max_num {
+ let mul = i * 5;
+ if mul >= max_num {
+ break;
+ }
+ reminder += 1;
+ if reminder == 3 {
+ reminder = 0;
+ } else {
+ sum += mul;
+ }
+ }
+ sum
+}
+
+fn method3(max_num: usize) -> usize {
+ let mut sum = 0;
+ let mut tmp = 0;
+ while tmp < max_num {
+ sum += tmp;
+ tmp += 3;
+ }
+ tmp = 0;
+ while tmp < max_num {
+ sum += tmp;
+ tmp += 5;
+ }
+ tmp = 0;
+ while tmp < max_num {
+ sum -= tmp;
+ tmp += 15;
+ }
+ sum
+}
+
+fn main() {
+ let max_num = 1000;
+ println!("sum in method1: {}", method1(max_num));
+ println!("sum in method2: {}", method2(max_num));
+ println!("sum in method3: {}", method3(max_num));
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(1000), 233_168));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(1000), 233_168));
+}
+
+#[bench]
+fn bench_method3(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method3(1000), 233_168));
+}
diff --git a/euler/rust/euler-002/Cargo.toml b/euler/rust/euler-002/Cargo.toml
new file mode 100644
index 00000000..414cb342
--- /dev/null
+++ b/euler/rust/euler-002/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "euler-002"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/euler/rust/euler-002/src/main.rs b/euler/rust/euler-002/src/main.rs
new file mode 100644
index 00000000..3e90266f
--- /dev/null
+++ b/euler/rust/euler-002/src/main.rs
@@ -0,0 +1,67 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// Each new term in the Fibonacci sequence is generated by adding the previous
+/// two terms. By starting with 1 and 2, the first 10 terms will be:
+/// 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
+/// By considering the terms in the Fibonacci sequence whose values do not
+/// exceed four million, find the sum of the even-valued terms.
+
+fn method1(max_num: usize) -> usize {
+ let mut sum = 0;
+ let mut prev = 1;
+ let mut current = 2;
+ let mut tmp;
+ let mut odd_num_count = 0;
+ while current <= max_num {
+ tmp = prev + current;
+ prev = current;
+ current = tmp;
+ odd_num_count += 1;
+ if odd_num_count == 1 {
+ sum += prev;
+ } else if odd_num_count == 3 {
+ odd_num_count = 0;
+ }
+ }
+
+ sum
+}
+
+fn method2(max_num: usize) -> usize {
+ let mut sum = 0;
+ let mut prev = 1;
+ let mut current = 2;
+
+ while current < max_num {
+ let new = prev + current;
+ prev = current;
+ current = new;
+ if prev % 2 == 0 {
+ sum += prev;
+ }
+ }
+ sum
+}
+
+fn main() {
+ let max_num = 4_000_000;
+ println!("sum: {}", method1(max_num));
+ println!("sum: {}", method2(max_num));
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(4_000_000), 4_613_732));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(4_000_000), 4_613_732));
+}
diff --git a/euler/rust/euler-004/Cargo.toml b/euler/rust/euler-004/Cargo.toml
new file mode 100644
index 00000000..f3f1e64f
--- /dev/null
+++ b/euler/rust/euler-004/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "euler-004"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/euler/rust/euler-004/src/main.rs b/euler/rust/euler-004/src/main.rs
new file mode 100644
index 00000000..1f8736fb
--- /dev/null
+++ b/euler/rust/euler-004/src/main.rs
@@ -0,0 +1,117 @@
+// Copyright (c) 2020 Xu Shaohua . All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#![feature(test)]
+extern crate test;
+
+/// Problem:
+///
+/// A palindromic number reads the same both ways. The largest palindrome made
+/// from the product of two 2-digit numbers is 9009 = 91 x 99.
+///
+/// Find the largest palindrome made from the product of two 3-digit numbers.
+
+fn method1() -> u32 {
+ let mut largest_palindrome = 0;
+ for i in (1..999).rev() {
+ for j in (1..i).rev() {
+ let product = i * j;
+ if is_palindrome1(product) {
+ if product > largest_palindrome {
+ largest_palindrome = product;
+ }
+ break;
+ } else if product < largest_palindrome {
+ break;
+ }
+ }
+ }
+ largest_palindrome
+}
+
+fn method2() -> u32 {
+ let mut largest_palindrome = 0;
+ for i in (1..999).rev() {
+ for j in (1..i).rev() {
+ let product = i * j;
+ if product < largest_palindrome {
+ break;
+ } else if is_palindrome2(product) {
+ if product > largest_palindrome {
+ largest_palindrome = product;
+ }
+ break;
+ }
+ }
+ }
+ largest_palindrome
+}
+
+fn is_palindrome1(num: u32) -> bool {
+ let s = num.to_string();
+ let rev_s: String = s.chars().rev().collect();
+ rev_s == s
+}
+
+fn is_palindrome2(num: u32) -> bool {
+ let mut mut_num = num;
+ let mut rev_num = 0;
+ while mut_num > 0 {
+ rev_num = rev_num * 10 + (mut_num % 10);
+ mut_num /= 10;
+ }
+ num == rev_num
+}
+
+fn main() {
+ println!("method1: {}", method1());
+ println!("method2: {}", method2());
+}
+
+#[bench]
+fn bench_method1(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method1(), 906609));
+}
+
+#[bench]
+fn bench_method2(b: &mut test::Bencher) {
+ b.iter(|| assert_eq!(method2(), 906609));
+}
+
+#[bench]
+fn bench_palindrome1(b: &mut test::Bencher) {
+ b.iter(|| {
+ for i in (1..999_999).step_by(10) {
+ is_palindrome1(i);
+ }
+ });
+}
+
+#[bench]
+fn bench_palindrome2(b: &mut test::Bencher) {
+ b.iter(|| {
+ for i in (1..999_999).step_by(1) {
+ is_palindrome2(i);
+ }
+ });
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn test_palindrome1() {
+ assert!(is_palindrome1(9009));
+ assert!(is_palindrome1(906609));
+ assert!(!is_palindrome1(98788));
+ }
+
+ #[test]
+ fn test_palindrome2() {
+ assert!(is_palindrome2(9009));
+ assert!(is_palindrome2(906609));
+ assert!(!is_palindrome2(98788));
+ }
+}