Data structure and algorithms

Exercising my problem solving skills by solving coding challenges and optimizing my result for best solution with data structures and complexity analysis.

Problems are categorized into folders named after their sources:

1. Leetcode
2. hackerRank

Index of solved leetcode questions

Before you run any test, please be sure that the test case does not have (x) before it, this means the test would be skipped. To run the test, remove the (x) letter.

javascript

Index	Question	Solution & Test	Difficulty	Tag	Topic
1	Two Sum	Solution	Easy	Array, Hash Table	ARRAY
2	Add Two Numbers	Solution	Medium	Math, Linked List, recursion	LINKED LIST
3	Longest Substring Without Repeating Characters	Solution	Medium	Hash table, string, sliding window	STRING
4	Median of Two sorted Arrays	Solution	Hard	Array, Binary Search, Divide and Conquer	ARRAY
5	Longest Palindromic Substring	Solution	Medium	String, Dynamic Programmming	STRING
7	Reverse Integer	Solution	Medium	Math	ARRAY
9	Palindrome Number	Solution	Easy	Math	ARRAY
13	Roman to Integer	Solution	Easy	Hashtable, Math, String	STRING
15	3Sum	Solution	Medium	Array, Two Pointers, Sorting	ARRAY
20	Valid Parentheses	Solution	Easy	Stack, String
21	Merge Two Sorted Lists	Solution	Easy	Linked List, Recursion
26	Remove Duplicates from Sorted Array	Solution	Easy	Array, Two Pointers
27	Remove Element	Solution	Easy	Array, Two Pointers
49	Group Anagrams	Solution	Medium	Hash Table, String, Sorting
53	Maximum Subarray	Solution	Easy	Array, Divide and Conquer, Dynamic Programming	Amazon
78	Subsets	Solution	Medium	Array, Backtracking, Bit manipulation
100	Same Tree	Solution	Easy	Tree, Depth-first search, Breadth-first search, Binary Tree
104	Maximum Depth of Binary Tree	Solution	Easy	Array, Depth-first search, Breadth-first search
110	Balanced Binary Tree	Solution	Easy	Tree, Depth-first search
121	Best Time to Buy and Sell Stock	Solution	Easy	Array, Dynamic Programming
122	Best Time to Buy and Sell Stock II	Solution	Easy	Array, Dynamic Programming, Greedy
125	Valid Palindrome	Solution	Easy	Two pointers, string
155	Min Stack	Solution	Easy	Stack, Design
167	Two Sum II - Input Array is sorted	Solution	Medium	Array, Two pointers, Binary Search
202	Happy Number	Solution	Easy	Hash Table, Math, Two Pointers
206	Reverse Linked List	Solution	Easy	Linked List, Recursion
208	Implement Trie (Prefix Tree)	Solution	Medium	Hash Table, String, Design, Trie
211	Design Add and Search Words Data Structure	Solution	Medium	Depth-first search, String, Design, Trie
215	Kth Largest Element in an Array	Solution	Medium	Array, Divide and Conquer, Sorting, Heap(Priority Queue), Quickselect
217	Contains Duplicate	Solution	Easy	Array, Hash Table, Sorting	Microsoft
219	Contains Duplicate II	Solution	Easy	Array, Hash Table, Sliding window	Google
225	Implement Stack Using Queue	Solution	Easy	Design, Stack, Queue
226	Invert Binary Tree	Solution	Easy	Depth first search, Breadth first search, Binary Tree
234	Palindrome Linked List	Solution	Easy	Linked List, Two Pointers, Stack, Recursion
327	Top K Frequent Elements	Solution	Medium	Array, Hash Table, Divide and Conquer, Sorting, Heap(Priority Queue), Bucket Sort, Counting, Quick Select
543	Diameter of Binary Tree	Solution	Easy	Tree, Depth first search, Binary Tree
581	Shortest Contiguous SubArray	Solution	Medium	Array, Two Pointers, Stack, Greedy, Monotonic Array, Sorting
703	Kth Largest Element in a Stream	Solution	Easy	Tree, Design, Binary Search Tree, Heap(Priority Queue), Binary Tree, Data Stream
704	Binary search	Solution	Easy	Array, Binary Search
905	Sort Array By Parity	Solution	Easy	Array, Two Pointers, Sorting
973	K Closest Points to Origin	Solution	Medium	Array, Math, Divide and Conquer, Heap(Priority Queue), Quickselect, Geometry, Sorting
1046	Last stone Weight	Solution	Easy	Array, Heap(Priority Queue)
1209	Remove All Adjacent Duplicates in String II	Solution	Medium	String, Stack	Amazon
1379	Find a Corresponding Node of a Binary Tree in a Clone of That Tree	Solution	Medium	Tree, Depth-first Search, Breadth-first Search, Binary Tree
1502	Can Make Arithmetic Progression From Sequence	Solution	Easy	Array, Sorting
1679	Max Number of K-Sum Pairs	Solution	Medium	Array, Sorting, Hash Table, Two Pointers
1790	Check if One String Swap Can Make Strings Equal	Solution	Easy	Hash Table, String, Counting
1822	Sign of the Product of an Array	Solution	Easy	Array, Math

Backtracking

No	LC Index	Question	Solution & Test	Difficulty	Tags
1	39	Combination Sum	Solution	Medium	Array, Backtracking, Depth First search, Recursion
2	46	Permutations	Solution	Medium	Array, Backtracking
3	78	Subsets	Solution	Medium	Array, Backtracking, Bit Manipulation
4	90	Subsets II	Solution	Medium	Array, Backtracking, Bit Manipulation

Matrix

No	LC Index	Question	Solution & Test	Difficulty	Tags
1	867	Transpose Matrix	Solution	Easy	Array, Matrix, Simulation
2	304	Range Sum Query 2D - Immutable	Solution	Medium	Array, Design, Matrix, Prefix Sum
3	51	N-Queens	Solution	Hard	Array, Backtracking
4	52	N-Queens II	Solution	Hard	Backtracking

Array

No	LC Index	Question	Solution & Test	Difficulty	Tags
1	1480	Running Sum of 1d Array	Solution	Easy	Array, Prefix sum
2	238	Product of Array Except Self	Solution	Medium	Array, Prefix sum
3	88	Merge sorted Array	Solution	Easy	Array, Two Pointers, Sorting
4	36	Valid Sudoku	Solution	Medium	Array, Hash Table, Matrix
5	167	Two Sum II - Input Array Is Sorted	Solution	Medium	Array, Two Pointers, Binary Search
6	2108	Find First Palindromic String in the Array	Solution	Easy	Array, Two-pointers, Strings
7	2016	Maximum Difference Between Increasing Elements	Solution	Easy	Array
8	1658	Minimum Operations to reduce x to zero	Solution	Medium	Array, Hash Table, Binary Search, Sliding window, Prefix sum
9	1658	Maximum Erasure Value	Solution	Medium	Array, Hash Table, Sliding window
10	128	Longest Consecutive Sequence	Solution	Medium	Array, Hash Table, Union Find
11	11	Container With Most Water	Solution	Medium	Array, Two Pointers, Greedy
12	42	Trapping Rain Water	Solution	Hard	Array, Two Pointers, Dynamic Programming, Stack, Monotonic Stack

Linked List

No	LC Index	Question	Solution & Test	Difficulty	Tags
1	160	Intersection of Two Linked List	Solution	Easy	Hash Table, Linked List, Two Pointers

Strings

No	LC Index	Question	Solution & Test	Difficulty	Tags
1	1332	Remove Palindromic Subsequence	Solution	Easy	String, Two Pointers
2	3	Longest Substring without repeating characters	Solution	Medium	String, Hash Table, Sliding window
3	-	Encode and decode strings	Solution	Medium	String, Design
4	424	Longest Repeating Character Replacement	Solution	Medium	Hash Table, String, Sliding Window

1-D Dynamic Programming

No	LC Index	Question	Solution & Test	Difficulty	Tags
1	70	Climbing Stairs	Solution	Easy	Math, Dynamic Programming, Memoization
2	583	Delete operation for two strings	Solution	Medium	String, Dynamic Programming
3	746	Min Cost Climbing Stairs	Solution	Easy	Array, Dynamic Programming

2-D Dynamic Programming

No	LC Index	Question	Solution & Test	Difficulty	Tags
1	120	Triangle	Solution	Medium	Array, Dynamic Programming
2	62	Unique Paths	Solution	Medium	Math, Dynamic Programming, Combinatorics

Graph

No	LC Index	Question	Solution & Test	Difficulty	Tags
1	200	Number of Islands	Solution	Medium	Graph, Depth First Search, Breadth First Search, Union Find, Matrix
2	1971	Find If Path Exists in Graph	Solution	Easy	Graph, Depth First Search, Breadth First Search
3	997	Find the town Judge	Solution	Easy	Array, Graph, Hash table
4	695	Max Area of Island	Solution	Medium	Array, Depth-First Search, Union Find, Matrix

Authors

🌸 Blossom

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