LeetCode Exercise

     

   

Array

ID	Title	Solution	Difficulty	Similar Questions
#0001	Two Sum	View	Easy	3Sum, Two Sum II, Two Sum III, Subarray Sum Equals K, Two Sum IV, Two Sum Less Than K
#0003	Longest Substring Without Repeating Characters	View	Medium	Longest Substring with At Most Two Distinct Characters, Longest Substring with At Most K Distinct Characters, Subarrays with K Different Integers
#0005	Longest Palindromic Substring	View	Medium	Shortest Palindrome, Palindrome Permutation, Palindrome Pairs, Longest Palindromic Subsequence, Palindromic Substrings
#0007	Reverse Integer	View	Easy	String to Integer (atoi), Reverse Bits
#0011	Container With Most Water	View	Meidum	Trapping Rain Water
#0015	3Sum	View	Medium	Two Sum, 3Sum Closest, 3Sum Smaller
#0016	3Sum Closest	View	Medium	3Sum, 3Sum Smaller
#0027	Remove Element	View	Easy	Remove Duplicates from Sorted Array, Remove Linked List Elements, Move Zeroes
#0031	Next Permutation	View	Medium	Permutations, Permutations II, Permutation Sequence, Palindrome Permutation II
#0088	Merge Sorted Array	View	Easy	Merge Two Sorted Lists, Squares of a Sorted Array, Interval List Intersections
#0165	Compare Version Numbers	View	Medium
#0167	Two Sum II	View	Easy	Two Sum, Two Sum IV, Two Sum Less Than K
#0170	Two Sum III	View	Easy	Two Sum, Unique Word Abbreviation, Two Sum IV
#0189	Rotate Array	View	Easy	Rotate List, Reverse Words in a String II
#0238	Product of Array Except Self	View	Medium	Trapping Rain Water, Maximum Product Subarray, Paint House II
#0259	3Sum Smaller	View	Medium	3Sum, 3Sum Closest, Valid Triangle Number, Two Sum Less Than K
#0268	Missing Number	View	Easy	First Missing Positive, Single Number, Find the Duplicate Number, Couples Holding Hands
#0274	H-z	View	Medium	H-Index II
#0283	Move Zeroes	View	Easy	Remove Element
#0380	Insert Delete GetRandom O(1)	View	Medium	Insert Delete GetRandom O(1) - Duplicates allowed
#0381	Insert Delete GetRandom O(1) - Duplicates allowed	View	Hard	Insert Delete GetRandom O(1)
#0485	Max Consecutive Ones	View	Easy	Max Consecutive Ones II, Max Consecutive Ones III, Consecutive Characters
#0487	Max Consecutive Ones II	View	Medium	Max Consecutive Ones, Max Consecutive Ones III
#0560	Subarray Sum Equals K	View	Medium	Two Sum, Continuous Subarray Sum, Subarray Product Less Than K, Find Pivot Index, Subarray Sums Divisible by K
#0628	Maximum Product of Three Numbers	View	Maximum Product Subarray
#1099	Two Sum Less Than K	View	Easy	Two Sum, Two Sum II, 3Sum Smaller, Subarray Product Less Than K

# 0442 | Find All Duplicates in an Array | View | Medium ||| 1437 | Check If All 1's Are at Least Length K Places Away | View | Medium | 0706 | Design Hash Map | View | Easy ||| 0705 | Design Hash Set | View | Easy ||| 1475 | Final Prices With a Special Discount in a Shop | View | Easy ||| 1277 | Count Square Submatrices with All Ones | View | Medium ||| 1475 | Final Prices With a Special Discount in a Shop | View | Easy ||| 0287 | Find the Duplicate Number | View | Medium ||| 1481 | Least Number of Unique Integers after K Removals | View | Medium ||| 0004 | Median of Two Sorted Arrays | View | Hard ||| 0918 | Maximum Sum Circular Subarray | View | Medium ||| 0496 | Next Greater Element I | View | Easy ||| 0503 | Next Greater Element II | View | Medium ||| 0556 | Next Greater Element III | View | Medium ||| 1338 | Reduce Array Size to The Half | View | Medium ||| 0905 | Sort Array By Parity | View | Easy ||| 0922 | Sort Array By Parity II | View | Easy ||| 1476 | Subrectangle Queries | View | Medium ||| 1471 | The k Strongest Values in an Array | View | Medium ||| 0941 | Valid Mountain Array | View | Medium |||

BFS (Breadth First Search)

ID	Title	Solution	Difficulty	Similar Questions
#0102	Binary Tree Level Order Traversal	View	Medium	Zigzag Level Traversal, Level Order Traversal II, Vertical Order Traversal, N-ary Level Order Traversal
#0126	Word Ladder II	View	Hard	Word Ladder
#0127	Word Ladder	View	Medium	Word Ladder II, Minimum Genetic Mutation
#0200	Number of Islands	View	Medium	Surrounded Regions, Walls and Gates, Number of Islands II, Number of Connected Components in an Undirected Graph, Number of Distinct Islands, Max Area of Island
#0286	Walls and Gates	View	Medium	Surrounded Regions, Number of Islands, Shortest Distance from All Buildings, Robot Room Cleaner, Rotting Oranges
#0433	Minimum Genetic Mutation	View	Medium	Word Ladder
#0505	The Maze II	View	Medium	The Maze, The Maze III
#0515	Find Largest Value in Each Tree Row	View	Medium
#0733	Flood Fill	View	Easy	Island Perimeter
#0818	Race Car	View	Hard
#0994	Rotting Oranges	View	Medium	Walls and Gates

Binary Search

ID	Title	Solution	Difficulty	Similar Questions
#0004	Median of Two Sorted Arrays	View	Hard
#0033	Search in Rotated Sorted Array	View	Medium	Search in Rotated Sorted Array II, Find Minimum in Rotated Sorted Array
#0034	Find First and Last Position of Element in Sorted Array	View	Medium	First Bad Version
#0069	Sqrt(x)	View	Easy	Pow(x, n), Valid Perfect Square
#0074	Search a 2D Matrix	View	Medium	Search a 2D Matrix II
#0081	Search in Rotated Sorted Array II	View	Medium	Search in Rotated Sorted Array
#0153	Find Minimum in Rotated Sorted Array	View	Medium	Search in Rotated Sorted Array, Find Minimum in Rotated Sorted Array II
#0154	Find Minimum in Rotated Sorted Array II	View	Hard	Find Minimum in Rotated Sorted Array
#0162	Find Peak Element	View	Medium	Peak Index in a Mountain Array
#0240	Search a 2D Matrix II	View	Medium	Search a 2D Matrix
#0278	First Bad Version	View	Easy	Find First and Last Position of Element in Sorted Array, Search Insert Position, Guess Number Higher or Lower
#0367	Valid Perfect Square	View	Easy	Sqrt(x), Sum of Square Numbers
#0374	Guess Number Higher or Lower	View	Easy	First Bad Version, Guess Number Higher or Lower II, Find K Closest Elements
#0744	Find Smallest Letter Greater Than Target	View	Easy
#0852	Peak Index in a Mountain Array	View	Easy	Find Peak Element, Find in Mountain Array
#1095	Find in Mountain Array	View	Hard	Peak Index in a Mountain Array

1482 | Minimum Number of Days to Make m Bouquets | View | Medium ||| 1300 | Sum of Mutated Array Closest to Target | View | Medium |||

DFS (Depth First Search)

ID	Title	Solution	Difficulty	Similar Questions
#0037	Sudoku Solver	View	Hard	Valid Sudoku, Unique Paths III
#0130	Surrounded Regions	View	Medium	Number of Islands, Walls and Gates
#0200	Number of Islands	View	Medium	Surrounded Regions, Walls and Gates, Number of Islands II, Number of Connected Components in an Undirected Graph, Number of Distinct Islands, Max Area of Island
#0490	The Maze	View	Medium	The Maze II, The Maze III
#0529	Minesweeper	View	Medium
1020	Number of Enclaves	View	Medium

Divide And Conquer

ID	Title	Solution	Difficulty	Similar Questions
#0315	Count of Smaller Numbers After Self	View	Hard	Count of Range Sum, Queue Reconstruction by Height, Reverse Pairs, How Many Numbers Are Smaller Than the Current Number
#0327	Count of Range Sum	View	Hard	Count of Smaller Numbers After Self, Reverse Pairs
#0493	Reverse Pairs	View	Hard	Count of Smaller Numbers After Self, Count of Range Sum

DP (Dynamic Programming)

ID	Title	Solution	Difficulty	Similar Questions
#0032	Longest Valid Parentheses	View	Hard	Valid Parentheses
#0053	Maximum Subarray	View	Easy	Best Time to Buy and Sell Stock, Maximum Product Subarray, Degree of an Array, Longest Turbulent Subarray
#0062	Unique Paths	View	Medium	Unique Paths II, Minimum Path Sum, Dungeon Game
#0063	Unique Paths II	View	Medium	Unique Paths, Unique Paths III
#0064	Minimum Path Sum	View	Medium	Unique Paths, Dungeon Game, Cherry Pickup
#0070	Climbing Stairs	View	Easy	Fibonacci Number, Min Cost Climbing Stairs, N-th Tribonacci Number
#0072	Edit Distance	View	Hard	One Edit Distance, Delete Operation for Two Strings, Minimum ASCII Delete Sum for Two Strings, Uncrossed Lines
#0091	Decode Ways	View	Medium	Decode Ways II
#0115	Distinct Subsequences	View	Hard
#0120	Triangle	View	Medium
#0121	Best Time to Buy and Sell Stock	View	Easy	Maximum Subarray, Best Time to Buy and Sell Stock II, Best Time to Buy and Sell Stock III, Best Time to Buy and Sell Stock IV, Best Time to Buy and Sell Stock with Cooldown
#0122	Best Time to Buy and Sell Stock II	View	Easy	Best Time to Buy and Sell Stock
#0123	Best Time to Buy and Sell Stock III	View	Hard	Best Time to Buy and Sell Stock, Best Time to Buy and Sell Stock II, Best Time to Buy and Sell Stock IV, Maximum Sum of 3 Non-Overlapping Subarrays
#0152	Maximum Product Subarray	View	Medium	Maximum Subarray, House Robber, Product of Array Except Self, Maximum Product of Three Numbers, Subarray Product Less Than K
#0188	Best Time to Buy and Sell Stock IV	View	Hard	Best Time to Buy and Sell Stock, Best Time to Buy and Sell Stock II, Best Time to Buy and Sell Stock III
#0198	House Robber	View	Easy	Maximum Product Subarray, House Robber II, Paint House, Paint Fence, House Robber III, Non-negative Integers without Consecutive Ones, Coin Path, Delete and Earn
#0213	House Robber II	View	Medium	House Robber, Paint House, Paint Fence, House Robber III, Non-negative Integers without Consecutive Ones, Coin Path
#0221	Maximal Square	View	Medium	Maximal Rectangle, Largest Plus Sign
#0279	Perfect Squares	View	Medium	Count Primes, Ugly Number II
#0300	Longest Increasing Subsequence	View	Medium	Increasing Triplet Subsequence, Russian Doll Envelopes, Maximum Length of Pair Chain, Number of Longest Increasing Subsequence, Minimum ASCII Delete Sum for Two Strings
#0309	Best Time to Buy and Sell Stock with Cooldown	View	Medium	Best Time to Buy and Sell Stock, Best Time to Buy and Sell Stock II
#0312	Burst Balloons	View	Hard	Minimum Cost to Merge Stones
#0322	Coin Change	View	Medium	Minimum Cost For Tickets
#0509	Fibonacci Number	View	Easy	Climbing Stairs, Split Array into Fibonacci Sequence, Length of Longest Fibonacci Subsequence, N-th Tribonacci Number
#0647	Palindromic Substrings	View	Medium	Longest Palindromic Substring, Longest Palindromic Subsequence
#0714	Best Time to Buy and Sell Stock with Transaction Fee	View	Medium	Best Time to Buy and Sell Stock II
#0746	Min Cost Climbing Stairs	View	Easy	Climbing Stairs
#0818	Race Car	[View]
#0887	Super Egg Drop	View	Hard
#1143	Longest Common Subsequence	View	Medium	Longest Palindromic Subsequence, Delete Operation for Two Strings, Shortest Common Supersequence
0518	Coin Change 2	View	Medium
0338	Counting Bits	View	Medium
0740	Delete and Earn	View	Medium
0174	Dungeon Game - Memoization	View	Hard
0174	Dungeon Game - Tabulation	View	Hard
0368	Largest Divisble Subset	View	Medium
0300	Longest Increasing Subsequence	View	Medium
1048	Longest String Chain	View	Medium
0978	Longest Turbulent Subarray	View	Medium
1035	Uncrossed Lines	View	Medium

Greedy Algorithm

ID	Title	Solution	Difficulty	Similar Questions
#0012	Integer to Roman	View	Medium	Roman to Integer, Integer to English Words
#0045	Jump Game II	View	Hard	Jump Game, Jump Game III
#0055	Jump Game	View	Medium	Jump Game II, Jump Game III
#0121	Best Time to Buy and Sell Stock	View	Easy	Maximum Subarray, Best Time to Buy and Sell Stock II, Best Time to Buy and Sell Stock III, Best Time to Buy and Sell Stock IV, Best Time to Buy and Sell Stock with Cooldown
#0122	Best Time to Buy and Sell Stock II	View	Easy
#0455	Assign Cookies	View	Easy
#0860	Lemonade Change	View	Easy	Best Time to Buy and Sell Stock, Best Time to Buy and Sell Stock III, Best Time to Buy and Sell Stock IV, Best Time to Buy and Sell Stock with Cooldown, Best Time to Buy and Sell Stock with Transaction Fee
#0874	Walking Robot Simulation	View	Easy

HashMap

ID	Title	Solution	Difficulty	Similar Questions
#0036	Valid Sudoku	View	Medium	Sudoku Solver
#0049	Group Anagrams	View	Medium	Valid Anagram, Group Shifted Strings
#0242	Valid Anagram	View	Easy	Group Anagrams, Palindrome Permutation, Find All Anagrams in a String

Heap

ID	Title	Solution	Difficulty	Similar Questions
#0023	Merge k Sorted Lists	View	Hard	Merge Two Sorted Lists, Ugly Number II
#0621	Task Scheduler	View	Medium	Rearrange String k Distance Apart, Reorganize String
#0675	Cut Off Trees for Golf Event	View	Hard
#1244	Design A Leaderboard	View	Meidum

Linked List

ID	Title	Solution	Difficulty	Similar Questions
#0002	Add Two Numbers	View	Medium	Multiply Strings, Add Binary, Sum of Two Integers, Add Strings, Add Two Numbers II, Add to Array-Form of Integer
#0021	Merge Two Sorted Lists	View	Easy	Merge k Sorted Lists, Merge Sorted Array, Sort List, Shortest Word Distance II
#0025	Reverse Nodes in k-Group	View	Hard	Swap Nodes in Pairs
#0138	Copy List with Random Pointer	View	Medium	Clone Graph, Clone Binary Tree With Random Pointer, Clone N-ary Tree
#0206	Reverse Linked List	View	Easy	Reverse Linked List II, Binary Tree Upside Down, Palindrome Linked List
0445	Add Two Numbers II	View	Medium
0707	Design Linked List	View	Medium
0141	Linked List Cycle	View	Easy
0142	Linked List Cycle II	View	Medium
0876	Middle of the Linked List	View	Easy
0021	Merge Two Sorted Lists	View	Easy
1019	Next Greater Node In Linked List	View	Medium
0328	Odd Even Linked List	View	Medium
0082	Remove Duplicates from Sorted List II	View	Medium
0061	Rotate List	View	Medium
0206	Reverse Linked List	View	Easy
0092	Reverse Linked List II	View	Medium
0019	Remove Nth Node From End of List	View	Medium
0024	Swap Nodes in Pairs	View	Medium

Recursion

ID	Title	Solution	Difficulty	Similar Questions
#0017	Letter Combinations of a Phone Number	View	Medium	Generate Parentheses, Combination Sum, Binary Watch
#0022	Generate Parentheses	View	Medium	Letter Combinations of a Phone Number, Valid Parentheses
#0050	Pow(x, n)	View	Medium	Sqrt(x), Super Pow
#0079	Word Search	View	Medium	Word Search II

Strings

ID	Title	Solution	Difficulty	Similar Questions
#0003	Longest Substring Without Repeating Characters	View	Medium	Longest Substring with At Most Two Distinct Characters, Longest Substring with At Most K Distinct Characters, Subarrays with K Different Integers
#0008	String to Integer (atoi)	View	Medium	Reverse Integer, Valid Number
#0013	Roman to Integer	View	Easy	Integer to Roman
#0028	Implement strStr()	View	Easy	Shortest Palindrome, Repeated Substring Pattern
#0048	Rotate Image	View	Medium
#0058	Length of Last Word	View	Easy
#0273	Integer to English Words	View	Hard	Integer to Roman
#0387	First Unique Character in a String	View	Easy	Sort Characters By Frequency
#0541	Reverse String II	View	Easy	Reverse String, Reverse Words in a String III
#0709	To Lower Case	View	Easy
#0771	Jewels and Stones	View	Easy
#0819	Most Common Word	View	Easy
#0937	Reorder Data in Log Files	View	Easy
1433	Check If a String Can Break Another String	View	Medium
0028	Implement strStr() - KMP Algorithm	View	Easy
0028	Implement strStr() - Rabin Karp Algorithm	View	Easy
0459	Repeated Substring Pattern - KMP Algorithm	View	Easy
0686	Repeated String Match - KMP Algorithm	View	Easy
1487	Making File Names Unique	View	Medium

Sliding Window

#	Title	Solution	Difficulty	Similar Questions
#0076	Minimum Window Substring	View	Hard	Substring with Concatenation of All Words, Minimum Size Subarray Sum, Sliding Window Maximum, Permutation in String, Smallest Range Covering Elements from K Lists, Minimum Window Subsequence
#0713	Subarray Product Less Than K	View	Medium	Maximum Product Subarray, Maximum Size Subarray Sum Equals k, Subarray Sum Equals K, Two Sum Less Than K
#1004	Max Consecutive Ones III	View	Medium	Longest Substring with At Most K Distinct Characters, Longest Repeating Character Replacement, Max Consecutive Ones, Max Consecutive Ones II
#1248	Count Number of Nice Subarrays	View	Medium
0904	Fruit Into Baskets	View	Medium
1052	Grumpy Bookstore Owner	View	Medium
1358	Number of Substrings Containing All Three Characters	View	Medium
1234	Replace the Substring for Balanced String	View	Medium

Sort

ID	Title	Solution	Difficulty	Similar Questions
#0056	Merge Intervals	View	Medium	Insert Interval, Meeting Rooms, Meeting Rooms II, Teemo Attacking, Add Bold Tag in String, Range Module, Employee Free Time, Partition Labels, Interval List Intersections
#0207	Course Schedule	View	Medium	Course Schedule II, Graph Valid Tree, Minimum Height Trees, Course Schedule III
#0210	Course Schedule II	View	Medium	Course Schedule, Alien Dictionary, Minimum Height Trees, Sequence Reconstruction, Course Schedule III
#0215	Kth Largest Element in an Array	View	Medium	Wiggle Sort II, Top K Frequent Elements, Third Maximum Number, Kth Largest Element in a Stream, K Closest Points to Origin
#1122	Relative Sort Array	View	Easy

Stack

ID	Title	Solution	Difficulty	Similar Questions
#0020	Valid Parentheses	View	Easy	Generate Parentheses, Longest Valid Parentheses, Remove Invalid Parentheses, Check If Word Is Valid After Substitutions
#0032	Longest Valid Parentheses	View	Hard	Valid Parentheses
#0042	Trapping Rain Water	View	Hard	Container With Most Water, Product of Array Except Self, Trapping Rain Water II, Pour Water
1381	Design a Stack With Increment Operation	View	Medium
0146	LRU Cache	View	Medium
0232	Implement Queue using Stacks	View	Easy
0155	Min Stack	View	Easy

Tree

ID	Title	Solution	Difficulty	Similar Questions
#0098	Validate Binary Search Tree	View	Medium	Binary Tree Inorder Traversal, Find Mode in Binary Search Tree
#0101	Symmetric Tree	View	Easy
#0102	Binary Tree Level Order Traversal	View	Medium	Minimum Depth of Binary Tree, Average of Levels in Binary Tree, Cousins in Binary Tree
#0103	Binary Tree Zigzag Level Order Traversal	View	Medium	Binary Tree Level Order Traversal
#0124	Binary Tree Maximum Path Sum	View	Hard	Path Sum, Sum Root to Leaf Numbers, Path Sum IV, Longest Univalue Path, Time Needed to Inform All Employees
#0236	Lowest Common Ancestor of a Binary Tree	View	Medium	Lowest Common Ancestor of a Binary Search Tree, Smallest Common Region
#0515	Find Largest Value in Each Tree Row	View	Medium
#0543	Diameter of Binary Tree	View	Easy	Diameter of N-Ary Tree
#0653	Two Sum IV	View	Easy	Two Sum, Two Sum II, Two Sum III, Two Sum BSTs
0938	Range Sum of BST	View	Easy
0617	Merge Two Binary Trees	View	Easy
0700	Search in a Binary Search Tree	View	Easy
0129	Sum Root to Leaf Numbers	View	Medium
0897	Increasing Order Search Tree	View	Easy
0559	Maximum Depth of N-ary Tree	View	Easy
0104	Maximum Depth of Binary Tree	View	Easy
0226	Invert Binary Tree	View	Easy
0530	Minimum Absolute Difference in BST	View	Easy
0993	Cousins in Binary Tree	View	Easy
0783	Minimum Distance Between BST Nodes	View	Easy
0543	Diameter of Binary Tree	View	Easy
0110	Balanced Binary Tree	View	Easy
0222	Count Complete Tree Nodes	View	Medium
1008	Construct Binary Search Tree from Preorder Traversal	View	Medium
1448	Count Good Nodes in Binary Tree	View	Medium
0889	Construct Binary Tree from Preorder and Postorder Traversal	View	Medium
0429	N-ary Tree Level Order Traversal	View	Medium
0230	Kth Smallest Element in a BST	View	Medium
0096	Unique Binary Search Trees	View	Medium

Trie

ID	Title	Solution	Difficulty	Similar Questions
#0208	Implement Trie (Prefix Tree)	View	Medium	Add and Search Word - Data structure design, Design Search Autocomplete System, Replace Words, Implement Magic Dictionary
#0212	Word Search II	View	Hard	Word Search, Unique Paths III

Union Find

ID	Title	Solution	Difficulty	Similar Questions
#0130	Surrounded Regions	View	Medium	Number of Islands, Walls and Gates
#0200	Number of Islands	View	Medium	Surrounded Regions, Walls and Gates, Number of Islands II, Number of Connected Components in an Undirected Graph, Number of Distinct Islands, Max Area of Island
#0547	Friend Circles	View	Medium	Number of Connected Components in an Undirected Graph, Robot Return to Origin, Sentence Similarity, Sentence Similarity II, The Earliest Moment When Everyone Become Friends
1319	Number of Operations to Make Network Connected	View	Medium
0684	Redundant Connection	View	Medium
0990	Satisfiability of Equality Equations	View	Medium