README.md

LeetCode Solution

Records of all my solved problems on LeetCode

Question #	Solution Link	Difficulty	Category	Demo	Language	LeetCode Link
1	twoSum	Easy	HashMap	False	Java	Two Sum
2	addTwoNums	Medium	Math	False	Java	Add Two Numbers
3	lenOfLongestSubstr	Medium	Sliding Window	True	Java	Longest Substring Without Repeating Characters
4	medianOf2SortedAry	Hard	Binary Search	True	Java	Median of Two Sorted Arrays
5	longestPalindrome	Medium	Dynamic Programming	True	Java	Longest Palindromic Substring
6	zigzagConversion	Medium	Str Traversal	True	Java	ZigZag Conversion
7	reverseInteger	Easy	Math	False	Java	Reverse Integer
8	atoi	Medium	Str Traversal, DFA	True	Java	String to Integer (atoi)
9	palindromeNum	Easy	Math	False	Java	Palindrome Number
10	regExpMatching	Hard	Dynamic Programming	True	Java	Regular Expression Matching
11	maxArea	Medium	Two Pointers	True	Java	Container With Most Water
12	intToRoman	Medium	Math	False	Java	Integer to Roman
13	romanToInt	Easy	Math	False	Java	Roman to Integer
14	lngstCommonPrefix	Easy	Str Traversal	False	Java, Python	Longest Common Prefix
15	threeSum	Medium	Two Pointers	False	Python	3Sum
16	threeSumClosest	Medium	Two Pointers	False	Python	3Sum Closest
17	phoneNumLetterComb	Medium	Math	True	Python	Letter Combinations of a Phone Number
18	fourSum	Medium	Two Pointers, Recursion	False	Python	4Sum
19	rmNthNodeFromEnd	Medium	LinkedList	True	Java	Remove Nth Node From End of List
20	validParentheses	Easy	Stack, Turing Machine	True	Python, Java	Valid Parentheses
21	mergeTwoSortedArys	Easy	LinkedList	False	Java	Merge Two Sorted Lists
22	generateParentheses	Medium	Dynamic Programming, Backtracking	True	Python	Generate Parentheses
23	mergeKsortedArys	Hard	Priority Queue, Divide & Conquer	True	Java	Merge k Sorted Lists
24	swapPairs	Medium	LinkedList, Recursion	False	Java	Swap Nodes in Pairs
25	reverseKgroup	Hard	LinkedList	True	Java	Reverse Nodes in k-Group
26	rmDuplicatesFromList	Easy	Two Pointers	False	Python	Remove Duplicates from Sorted Array
27	rmElementsFromList	Easy	Two Pointers	False	Python	Remove Element
28	implementIndexOf	Easy	Sliding Window, Two Pointers	True	Python	Implement strStr()
29	divideTwoInts	Medium	Bit Manipulation	False	Java	Divide Two Integers
30	findSubstr	Hard	HashMap	True	Python	Substring with Concatenation of All Words
31	nextPermutation	Medium	Math	True	Python	Next Permutation
32	lngstValidParentheses	Hard	Stack, Dynamic Programming	True	Python	Longest Valid Parentheses
33	searchRotatedSortedAry	Medium	Binary Search	True	Python	Search in Rotated Sorted Array
34	searchRangeInSortedAry	Medium	Binary Search	False	Python	Find First and Last Position of Element in Sorted Array
35	searchInsertPos	Easy	Binary Search	False	Python	Search Insert Position
36	validSudoku	Medium	HashSet	False	Python	Valid Sudoku
37	solveSudoku	Hard	Backtracking	False	Python	Sudoku Solver
38	countAndSay	Medium	Str Traversal	True	Java	Count and Say
39	combinationSum	Medium	Backtracking, Dynamic Programming	True	Java	Combination Sum
40	combinationSum II	Medium	Backtracking, Dynamic Programming	False	Java	Combination Sum II
41	firstMissingPositive	Hard	In-place Hashing	True	Java	First Missing Positive
42	trappingRainWater	Hard	Dynamic Programming	True	Java, Python	Trapping Rain Water
43	multiplyStrings	Medium	Math	True	Python	Multiply Strings
44	wildcardMatching	Hard	Backtracking, Dynamic Programming	True	Python	Wildcard Matching
45	jumpGame2	Medium	Greedy Algorithm	True	Java	Jump Game II
46	permutations	Medium	DFS	True	Python, C++	Permutations
47	permutations2	Medium	DFS	False	Python	Permutations II
48	rotateImage	Medium	List Manipulation	True	Python	Rotate Image
49	groupAnagrams	Medium	HashMap	False	Python	Group Anagrams
50	pow(x, n)	Medium	Binary Exponentiation	True	Python	Pow(x, n)
51	n-queens	Hard	Backtracking	False	Python	N-Queens
52	n-queens 2	Hard	Backtracking	False	Python	N-Queens II
53	maximumSubarray	Easy	Dynamic Programming	True	Java	Maximum Subarray
54	spiralMatrix	Medium	List Traversal	False	Python	Spiral Matrix
55	jumpGame	Medium	Greedy Algorithm, Backtracking	False	Python	Jump Game
56	mergeIntervals	Medium	List Traversal	False	Python	Merge Intervals
57	insertIntervals	Medium	List Traversal	False	Python	Insert Interval
58	lengthOfLastWord	Easy	Str Traversal	False	Python	Length of Last Word
59	spiralMatrix II	Medium	List Traversal	False	Python	Spiral Matrix II
60	permutationSeq	Hard	Math	True	Python	Permutation Sequence
61	rotateList	Medium	LinkedList	False	Python	Rotate List
62	uniquePaths	Medium	DFS, Recursion	False	Python	Unique Paths
63	uniquePaths II	Medium	Dynamic Programming	True	Python	Unique Paths II
64	minPathSum	Medium	Dynamic Programming	False	Python	Minimum Path Sum
65	validNumber	Hard	DFA	True	Python	Valid Number
66	plusOne	Easy	Math	False	Python	Plus One
67	addBinary	Easy	Math	False	Python	Add Binary
68	textJustification	Hard	List Traversal	False	Python	Text Justification
69	sqrt(x)	Easy	Math	False	Python	Sqrt(x)
70	climbStairs	Easy	Math	False	Python	Climbing Stairs
71	simplifyPath	Medium	Str Traversal	False	Python	Simplify Path
72	editDistance	Hard	Dynamic Programming	True	Python	Edit Distance
73	setMatrixZero	Medium	List Traversal	True	Python	Set Matrix Zeroes
74	searchMatrix	Medium	Binary Search, List Traversal	False	Python	Search a 2D Matrix
75	sortColors	Medium	Two Pointers, Sorting	False	Python	Sort Colors
76	minWindow	Hard	Two Pointers	False	Python	Minimum Window Substring
77	combinations	Medium	Backtracking	False	Python	Combinations
78	subsets	Medium	Backtracking, Cascading	True	Python	Subsets
79	wordSearch	Medium	Backtracking	False	Python	Word Search
80	rmDupFromSortedAry II	Medium	Two Pointers	True	Python	Remove Duplicates from Sorted Array II
81	searchRotatedSortedAry II	Medium	Binary Search	False	Python	Search in Rotated Sorted Array II
82	rmDupFromSortedLst II	Medium	Two Pointers	False	Python	Remove Duplicates from Sorted List II
83	rmDupFromSortedLst	Easy	LinkedList, Recursion	True	Python	Remove Duplicates from Sorted List
84	largestRecInHist	Hard	Stack	False	Python	Largest Rectangle in Histogram
85	maxRec	Hard	Dynamic Programming	False	Python	Maximal Rectangle
86	partitionList	Medium	LinkedList, Two Pointers	False	Python	Partition List
87	scrambleString	Hard	Recursion	True	Python	Scramble String
88	mergeSortedAry	Easy	List Traversal	False	Python	Merge Sorted Array
89	grayCode	Medium	Bit Manipulation	False	Python	Gray Code
90	subsets II	Medium	DFS	False	Python	Subsets II
91	decodeWays	Medium	DFS, Dynamic Programming	True	Python	Decode Ways
92	reverseLinkedList II	Medium	LinkedList	False	Python	Reverse Linked List II
93	restoreIPaddr	Medium	Backtracking	False	Python	Restore IP Addresses
94	inorderTraversal	Easy	Binary Tree, DFS	True	Python	Binary Tree Inorder Traversal
95	uniqueBST II	Medium	Binary Tree, Recursion	True	Python	Unique Binary Search Trees II
96	uniqueBST	Medium	Dynamic Programming, Binary Tree	True	Python	Unique Binary Search Trees
97	interleavingStr	Medium	Dynamic Programming, Backtracking, DFS	False	Python	Interleaving String
98	validateBST	Medium	DFS, BFS, BST	False	Python	Validate Binary Search Tree
99	recoverBST	Medium	DFS, BST	False	Python	Recover Binary Search Tree
100	sameTree	Medium	DFS, BST	False	Python	Same Tree
101	symmetricTree	Easy	DFS, BST	False	Python	Symmetric Tree
102	levelOrderTraversal	Mediumn	BFS, BST	False	Python	Binary Tree Level Order Traversal
103	BTzigzagTraversal	Mediumn	BFS, BST	False	Python	Binary Tree Zigzag Level Order Traversal
104	maxDepthBST	Easy	DFS, BST	False	Python	Maximum Depth of Binary Tree
105	treeFromPre&Inorder	Medium	BST	False	Python	Construct Binary Tree from Preorder and Inorder Traversal
106	treeFromIn&Postorder	Medium	BST	False	Python	Construct Binary Tree from Inorder and Postorder Traversal
107	lvlOrderTraversal II	Medium	BFS, BST	False	Python	Binary Tree Level Order Traversal II
108	cvtSortedAryToBST	Easy	BST	False	Python	Convert Sorted Array to Binary Search Tree
109	cvtSortedLnkedListToBST	Medium	BST	False	Python	Convert Sorted List to Binary Search Tree
110	balancedBinaryTree	Easy	DFS	False	Python	Balanced Binary Tree
111	minDepthOfBinaryTree	Easy	DFS	False	Python	Minimum Depth of Binary Tree
112	pathSum	Easy	DFS	False	Python	Path Sum
113	pathSum II	Medium	DFS	False	Python	Path Sum II
114	flattenBT2LinkedList	Medium	Binary Tree	True	Python	Flatten Binary Tree to Linked List
115	distinctSubseq	Hard	DFS, Dynamic Programming	False	Python	Distinct Subsequences
116	populatingNextPtr	Medium	BFS	False	Python	Populating Next Right Pointers in Each Node
117	populatingNxtPtr II	Medium	BFS	False	Python	Populating Next Right Pointers in Each Node II
118	Pascal's triangle	Easy	Math	False	Python	Pascal's Triangle
119	Pascal's triangle II	Easy	Math	False	Python	Pascal's Triangle II
120	minTotalTriangle	Medium	Dynamic Programming	True	Python	Triangle
121	bestTimeToBuyAndSell	Easy	Two Pointers	True	Python	Best Time to Buy and Sell Stock
122	bestTimeToBuyAndSell II	Medium	Greedy Algorithm	True	Python	Best Time to Buy and Sell Stock II
123	bestTimeToBuyAndSell III	Hard	Dynamic Programming	False	Python	Best Time to Buy and Sell Stock III
124	BTMaxPathSum	Hard	Recursion	False	Python	Binary Tree Maximum Path Sum
125	validPalindrome	Easy	Two Pointers	False	Python	Valid Palindrome
126	wordLadder II	Hard	BFS	False	Python	Word Ladder II
127	wordLadder	Hard	BFS, Bidirectional BFS	True	Python	Word Ladder
128	longestConsecutiveSeq	Medium	List Traversal	True	Python	Longest Consecutive Sequence
129	root2LeafNumSum	Medium	DFS	False	Python, C++	Sum Root to Leaf Numbers
130	surroundedRegions	Medium	DFS	False	C++	Surrounded Regions
131	partitionPalindrome	Medium	DFS, Backtracking	True	C++	Palindrome Partitioning
132	partitionPalindromeII	Hard	Dynamic Programming	True	C++	Palindrome Partitioning II
133	cloneGraph	Medium	DFS	False	C++	Clone Graph
134	gasStation	Medium	Greedy	False	C++	Gas Station
135	candy	Hard	Greedy	False	C++	Candy
136	singleNumber	Easy	Bit Manipulation	False	C++	Single Number
137	singleNumber II	Medium	Bit Manipulation, Logic Circuit	True	C++	Single Number II
138	copyLstW/RandomPtr	Medium	LinkedList, Map	True	C++	Copy List with Random Pointer
139	wordBreak	Medium	Dynamic Programming	True	C++	Word Break
140	wordBreak II	Hard	Backtracking	False	C++	Word Break II
141	linkedListCycle	Easy	LinkedList	False	C++	Linked List Cycle
142	linkedListCycle II	Medium	Two Pointers, LinkedList	True	C++	Linked List Cycle II
143	reorderList	Medium	Two Pointers, LinkedList	False	C++	Reorder List
144	preorderTraversal	Easy	Recursion, Morris Traversal, Stack	True	C++	Binary Tree Preorder Traversal
145	postorderTraversal	Easy	Recursion, Stack	False	C++	Binary Tree Postorder Traversal
146	LRUCache	Medium	LinkedList	False	C++	LRUCache
147	insertionSortList	Medium	LinkedList	False	C++	Insertion Sort List
148	sortList	Medium	Merge Sort, LinkedList	False	C++	Sort List
149	maxPtsOnLine	Hard	Math	False	Python	Max Points on a Line
150	evalRevPolishNotation	Medium	Stack	False	Python	Evaluate Reverse Polish Notation
151	reverseWordsInStr	Medium	Str Manipulation	True	C++	Reverse Words in a String
152	maxProductSubarray	Medium	Dynamic Programming	False	Python	Maximum Product Subarray
153	findMinInRotatedSortedAry	Medium	Binary Search	False	Python	Find Minimum in Rotated Sorted Array
154	findMinInRotatedSortedAry II	Hard	Binary Search	False	Python	Find Minimum in Rotated Sorted Array II
155	minStack	Medium	Stack	False	Python	Min Stack
160	intersecionOf2LL	Easy	LinkedList	False	Python	Intersection of Two Linked Lists
162	findPeakElement	Medium	Binary Search	False	Python	Find Peak Element
164	maxGap	Hard	Bucket Sort	False	Python	Maximum Gap
165	compareVersionNums	Medium	List Traversal	False	Python	Compare Version Numbers
166	fractionToDecimal	Medium	Math	True	Python	Fraction to Recurring Decimal
167	twoSum II	Medium	Two Pointers	False	Python	Two Sum II - Input Array Is Sorted
168	excelSheetColTitle	Easy	Math	False	Python	Excel Sheet Column Title
169	majorityElement	Easy	List Traversal	False	Python	Majority Element
171	excelSheetColNum	Easy	Math	True	Python, C++	Excel Sheet Column Number
172	factorialTrailingZeroes	Medium	Math	False	Python	Factorial Trailing Zeroes
173	BSTIterator	Medium	BST	False	Python	Binary Search Tree Iterator
174	dungeonGame	Hard	Dynamic Programming	False	Python	Dungeon Game
175	combineTwoTables	Easy	SQL	False	SQL	Combine Two Tables
176	secondHighestSalary	Medium	SQL	False	SQL	Second Highest Salary
177	NthHighestSalary	Medium	SQL	False	SQL	Nth Highest Salary
178	rankScores	Medium	SQL	False	SQL	Rank Scores
179	largestNumber	Medium	Sorting	False	Python	Largest Number
180	consecutiveNumbers	Medium	SQL	False	SQL	Consecutive Numbers
181	employeeWithHigherSalary	Easy	SQL	False	SQL	Employees Earning More Than Their Managers
182	duplicateEmails	Easy	SQL	False	SQL	Duplicate Emails
183	customersWithoutOrders	Easy	SQL	False	SQL	Customers Who Never Order
184	departmentHighestSalary	Medium	SQL	False	SQL	Department Highest Salary
185	departmentTop3Salaries	Hard	SQL	False	SQL	Department Top Three Salaries
187	repeatedDNASequences	Medium	Sliding Window	False	Python	Repeated DNA Sequences
188	bestTimeToBuyAndSell IV	Hard	Dynamic Programming	False	Python	Best Time to Buy and Sell Stock IV
189	rotateArray	Medium	Array	False	Python	Rotate Array
190	reverseBits	Easy	Bit Manipulation	False	Python	Reverse Bits
191	1BitsCount	Easy	Bit Manipulation	False	Python	Number of 1 Bits
198	houseRobber	Medium	Dynamic Programming	False	Python	House Robber
200	numIslands	Medium	DFS	False	Python	Number of Islands
206	reverseLinkedList	Easy	LinkedList	True	Python	Reverse Linked List
208	Trie	Medium	Trie	False	C++	Implement Trie (Prefix Tree)
213	houseRobber 2	Medium	Dynamic Programming	True	C++	House Robber II
215	kthLargestElementInAry	Medium	Quickselect	True	Python	Kth Largest Element in an Array
221	maxSquare	Medium	Dynamic Programming	False	Python	Maximal Square
290	wordPattern	Easy	HashMap	False	Python, C++	Word Pattern
322	coinChange	Medium	DFS, Dynamic Programming	False	C++	Coin Change
332	reconstructIternary	Hard	Stack, Backtracking	False	Python	Reconstruct Itinerary
337	houseRobber 3	Medium	DFS Memorization	False	C++	House Robber III
359	loggerRateLimiter	Easy	Hash	False	Python	Logger Rate Limiter
366	findLeavesOfBST	Medium	Binary Tree, DFS	False	Python	Find Leaves of Binary Tree
418	screenSentenceFitting	Medium	List Traversal	False	Python	Sentence Screen Fitting
450	deleteNodeInBST	Medium	BST	False	Python	Delete Node in a BST
678	validParenthesisStr	Medium	DFS, Dynamic Programming, Greedy	False	Python	Valid Parenthesis String
690	employeeImportance	Easy	BFS, DFS	False	Python	Employee Importance
696	countBinarySubstr	Easy	Two Pointers	True	Python	Count Binary Substrings
735	asteroidCollision	Medium	Stack	False	Python	Asteroid Collision
753	crackSafe	Hard	Backtracking, Hierholzer Algorithm, Eulerian Cycle	True	C++	Cracking the Safe
787	cheapestFlights	Medium	Bellman Ford's Algorithm, Dijkstra's Algorithm, Dynamic Programming	False	C++	Cheapest Flights Within K Stops
792	numOfMatchingSubseq	Medium	Binary Search, Pointer	False	Python	Number of Matching Subsequences
833	find&ReplaceInStr	Medium	String Manipulation	False	Python	Find And Replace in String
843	guessWord	Hard	Game Theory	False	Python	Guess the Word
853	carFleet	Medium	List Traversal	False	Python	Car Fleet
923	threeSumMulti	Medium	Two Pointers, Math	True	C++	3Sum With Multiplicity
931	minFallingPathSum	Medium	Dynamic Programming	False	Python	Minimum Falling Path Sum
981	timeBasedKeyValStore	Medium	Binary Search	False	Python	Time Based Key-Value Store
983	minCostsForTickets	Medium	Dynamic Programming, DFS	False	Python	Minimum Cost For Tickets
1004	maxConsecutiveOnes III	Medium	Sliding Window	False	Python	Max Consecutive Ones III
1048	longestStrChain	Medium	Dynamic Programming, DFS	False	Python	Longest String Chain
1110	delNodes&ReturnForest	Medium	DFS	False	Python	Delete Nodes And Return Forest
1146	snapshotArray	Medium	Binary Search	False	Python	Snapshot Array
1278	palindromePartitioning III	Hard	Dynamic Programming, DFS Memorization	True	C++	Palindrome Partitioning III
1423	maxPointsFromCards	Medium	Sliding Window, Two Pointers	False	Python	Maximum Points You Can Obtain from Cards
1428	minDaysBloom	Medium	Binary Search	False	Python	Minimum Number of Days to Make m Bouquets
1509	minDiffBetMax&Min	Medium	Backtracking	False	Python	Minimum Difference Between Largest and Smallest Value in Three Moves
1525	numOfWaysToSplitStr	Medium	HashMap	False	Python	Number of Good Ways to Split a String
1526	minNumOfIncrement	Hard	Dynamic Programming	True	Python	Minimum Number of Increments on Subarrays to Form a Target Array
1548	mostSimilarPath	Hard	Dynamic Programming	True	Python	The Most Similar Path in a Graph
1610	maxNumVisiblePts	Hard	Sliding Window, Geometry	False	Python	Maximum Number of Visible Points
1776	carFleet II	Hard	Stack, Monotonic Stack	False	Python	Car Fleet II
1834	singleThreadedCPU	Medium	Min-Heap, Priority Queue	False	C++	Single-Threaded CPU
1937	maxPointsWithCost	Medium	Dynamic Programming	False	Python	Maximum Number of Points with Cost

Other Questions

Question	Solution Link	Category	Demo	Language
Permutation of if-blocks	ifBlockPermutations	DFS, Backtracking	False	Python
Image Matching	imageMatching	Stack, DFS	False	Python
Remove B	removeB	DFS	False	Python
Inversion	Inversion	Dynamic Programming, Backtracking	False	Python
Shortest Rainbow Path	shortestRainbowPath	Dijkstra's algorithm	False	Python
Knapsack Problem	knapsack	Genetic Algorithm, Dynamic Programming	False	Python, C++
Min Health	getMinHealth	Priority Queue	False	Python
Visiting Cities	minCost	Dynamic Programming	False	Python