Got stuck in a LeetCode question? This repository will help you by providing approach of solving the problems from LeetCode platform.
Contributors helped us in providing these Awesome solutions.
If you want to contribute, please create a Pull Request. If you are new to Github please check pull request procedure ---> PR process
Check out ---> Sample PR
- There are new LeetCode questions every week. I'll keep updating for full summary and better solutions.
- For more challenging problem solutions, you can also see our HackerRank-Solutions, ProjectEuler repositories.
- Hope you enjoy the journey of learning data structures and algorithms.
- Notes: "🔒" means your subscription of LeetCode premium membership is required for reading the question.
Check out -> Learning Resources
- Bit Manipulation
- Array
- String
- Linked List
- Stack
- Queue
- Heap
- Tree
- Hash Table
- Math
- Two Pointers
- Sort
- Recursion
- Binary Search
- Binary Search Tree
- Breadth-First Search
- Depth-First Search
- Backtracking
- Dynamic Programming
- Greedy
- Graph
- Geometry
- Simulation
- Design
- Concurrency
| # | Title | Solution | Time | Space | Difficulty | Tag | Tutorial |
|---|---|---|---|---|---|---|---|
| 0136 | Single Number | Java Python C++ |
O(n) | O(1) | Easy | Using XOR | |
| 260 | Single Number III | Python | O(n) | O(1) | Medium | ||
| 476 | Number Complement | Java | O(1) | O(1) | Easy | Tutorial | |
| 520 | Detect Capital Use | Python | O(n) | O(1) | Easy |
| # | Title | Solution | Time | Space | Difficulty | Note | Video Explaination |
|---|---|---|---|---|---|---|---|
| 56 | Merge Intervals | Python | O(nlogn) | O(n) | Medium | Intervals | |
| 268 | Missing Number | Java | O(n) | O(1) | Easy | Array | Tutorial |
| 697 | Degree of an Array | Java | O(n) | O(n) | Easy | Array | |
| 1089 | Duplicate Zeroes | JavaScript | O(n) | O(n) | Easy | Array | |
| 1502 | Can Make Arithmetic Progression From Sequence | Java | O(n) | O(1) | Easy | Array | |
| 122 | Best Time to buy and sell Stock II | Python C++ |
O(N) | O(1) | Medium | Stocks | |
| 119 | Pascal's Triangle II | Python | O(N^2) | O(K) | Easy | ||
| 1480 | Running Sum of 1d Array | Java | O(N) | O(N) | Easy | Simple sum | |
| 42 | Trapping Rain Water | Python | O(N^2) | O(N) | Hard | Array | |
| 11 | Container with Most Water | Python | O(N) | O(N) | Medium | Array Two Pointers | |
| 1134 🔒 | Armstrong Number | Java | O(N) | O(1) | Easy | ||
| 1534 | Count Good Triplets | Python | O(N^3) | O(1) | Easy | ||
| 1572 | Matrix Diagonal Sum | Java | O(N) | O(1) | Easy | ||
| 811 | Subdomain Visit Count | Javascript | O(N*M) | O(N*M + N) | Easy | ||
| 53 | Maximum Subarray | C++ | O(N) | O(1) | Easy | Array | |
| 495 | Teemo Attacking | C++ | O(n) | O(1) | Medium | Array | |
| 15 | 3 Sum | Python | O( nLog(n) ) | O(1) | Medium | Array | |
| 1200 | Minimum Absolute Difference | Python | O(n) | O(1) | Easy | Array | |
| 532 | K-diff Pairs in an Array | C++ | O(n) | O(n) | Medium | Array | |
| 152 | Maximum Product Subarray | Javascript | O(n) | O(n) | Medium | Array | |
| 073 | Set-Matrix-Zeroes | Java | O(MN) | O(1) | Medium | Array | |
| 1288 | Remove-Covered-Intervals | C++ | O(N*N) | O(1) | Medium | Array |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 383 | Ransom Note | Java | O(1) | O(n) | Easy | Character Count | |
| 387 | First Unique Character in a String | Java | O(n) | O(1) | Easy | Character Count | |
| 151 | Reverse Words in a String | Java | O(1) | O(n) | Medium | ||
| 520 | Detect Capital Use | Java | O(n) | O(1) | Easy | ||
| 1221 | Split a String in Balanced Strings | Python | O(n) | O(1) | Easy |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 002 | Add Two Numbers | Java | O(n) | O(n) | Medium | Math | |
| 19 | Remove Nth Node From End of List | Java | O(n) | O(1) | Medium | Two pointers | |
| 109 | Convert Sorted List to Binary Search Tree | Java | O(n) | O(n) | Medium | LinkedList | |
| 141 | Linked List Cycle | Java | O(n) | O(1) | Easy | Slow-Fast Pointers | |
| 142 | Linked List Cycle II | Java C++ |
O(n) | O(1) | Medium | Slow-Fast Pointers | |
| 146 | LRU Cache | C++ | O(1) | O(k) | Medium | Hash Map | |
| 186 | Middle of the Linked List | Java | O(n) | O(1) | Easy | Two pointers | |
| 23 | Merge K sorted lists | C++ | O(nlogn) | O(n) | Hard | sorting and append |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 020 | Valid Parentheses | Python | O(n) | O(n) | Easy | Stack | |
| 150 | Evaluate Reverse Polish Notation | Python | O(n) | O(1) | Medium | Stack | |
| 1047 | Remove All Adjacent Duplicates In String | C++ | O(n) | O(n) | Easy | Stack | |
| 682 | Baseball Game | C++ | O(n) | O(n) | Easy | Stack | |
| 1381 | Design a Stack With Increment Operation | Java | O(n) | O(n) | Medium | Stack | |
| 1598 | Crawler Log Folder | C++ | O(n) | O(n) | Easy | Stack |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 933 | Number of Recent Calls | C++ | O(1) | O(1) | Easy | Queue, Sliding Window |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 094 | Binary Tree Inorder Traversal | Java | O(n) | O(logn) | Medium | Binary Tree, Stack, HashTable | |
| 100 | Same Tree | Python | O(n) | O(n) | Easy | Tree, Depth-first Search | |
| 101 | Symmetric Tree | Java Python |
O(n) | O(n) | Easy | Tree, Breadth-first Search, Depth-first Search | |
| 144 | Binary Tree Preorder Traversal | Java | O(n) | O(logn) | Medium | Binary Tree, Stack | |
| 145 | Binary Tree Postorder Traversal | Java | O(n) | O(logn) | Hard | Binary Tree, Stack | |
| 103 | ZigZag Level Order | JavaScript C++ |
O(n) | O(n) | Medium | Binary Tree | |
| 129 | Sum Root to Leaf Numbers | Java | O(n) | O(logn) | Medium | Binary Tree, Depth First Search | |
| 307 | Range Sum Query - Mutable | Java | O(logn) | O(n) | Medium | Segment Tree | |
| 919 | Complete Binary Tree Inserter | Java | O(n) | O(n) | Medium | Tree | |
| 124 | Binary Tree Maximum Path Sum | C++ | O(n) | O(n) | Hard | Tree | |
| 1028 | Recover a Tree From Preorder Traversal | C++ | O(n) | O(n) | Hard | Tree | |
| 968 | Binary Tree Cameras | C++ | O(n) | O(logn) | Hard | Binary Tree, Dynamic Programming | |
| 98 | Validate Binary Search Tree | Javascript | O(log(n)) | O(log(n)) | Medium | Binary Tree |
| # | Title | Solution | Time | Space | Difficulty | Tag | Video Explanation |
|---|---|---|---|---|---|---|---|
| 001 | Two Sum | Java Python C++ |
O(N) | O(N) | Easy | Tutorial | |
| 242 | Valid Anagram | Java | O(n) | O(1) | Easy | Tutorial | |
| 146 | LRU Cache | Java | Medium | ||||
| 217 | Contains Duplicate | Python | O(n) | O(n) | |||
| 554 | Brick Wall | C++ | O(n) | O(n) | Medium | ||
| 049 | Group Anagrams | Python | O(nlogn) | O(1) | Easy | ||
| 554 | Brick Wall | C++ | O(n) | O(n) | Medium | ||
| 146 | LRU Cache | Javascript | O(log(n)) | O(n) | Medium |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 005 | Longest Palindromic Substring | Python JavaScript |
O(N^2) O(N^2) |
O(N) O(1) |
Medium | Expand the Wings | |
| 4 | Median of Two Sorted Arrays | Java | O(log(min(m,n))) | O(1) | Hard | ||
| 845 | Longest Mountain in Array | C++ | O(N) | O(1) | Medium | Two Pointer |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 050 | Pow(x, n) | Python JavaScript |
O(n) | O(1) | Medium | Math | |
| 204 | Count Primes | C++ | O(n(log(logn))) | O(n) | Easy | Math | |
| 168 | Excel Sheet Column Title | C++ | O(n) | O(n) | Easy | String | |
| 007 | Reverse Integer | Java C++ |
O(n) | O(n) | Easy | Math | |
| 202 | Happy Number | Java | O(n^2) | O(n) | Easy | Math | |
| 326 | Power of Three | Java | O(logn) | O(n) | Easy | Math | |
| 12 | Integer to Roman | Java | O(n) | O(1) | Medium | Math | |
| 13 | Roman to Integer | Java | O(n) | O(1) | Easy | Math |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 1284 | Minimum Number of Flips to Convert Binary Matrix to Zero Matrix | C++ | O(m * n * 2 ^ (m * n)) | O(2 ^ (m * n)) | Hard | BFS | |
| 200 | Number of Islands | Java | O(R * C) | O(R * C) | Medium | BFS | |
| 127 | Word Ladder | Java | O(N^2 * M) | O(N * M) | Medium | BFS | |
| 994 | Rotten Oranges | Python | O(N * M) | O(N * M) | Medium | BFS |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 1463 | Cherry Pickup II | C++ | O(n * m) | O(n * m) | Hard | DFS |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 037 | Sudoku Solver | C++ | O(n^2) | O(1) | Hard | Hash Table | |
| 980 | Unique Paths III | C++ | O(R * C * 2 ^ (R * C)) | O(R * C) | Hard | DFS, Memoization | |
| 39 | Combination Sum | C++ | O(2^n) | O(n) | Medium | Array, Backtracking |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 416 | Partition Equal Subset Sum | C++ | O(n^2) | O(n^2) | Medium | DP | |
| 056 | Wildcard Matching | Python | O(n^2) | O(n^2) | Hard | ||
| 343 | Integer Break | C++ | O(n^2) | O(n) | Medium | ||
| 139 | Word Break | Python | O(n^3) | O(n) | Medium | DP | |
| 1092 | Shortest Common Supersequence | C++ | O(n^2) | O(n^2) | Hard | DP | |
| 72 | Edit Distance | Python | O(N*M) | O(n^2) | Medium | Levenshtein Distance | |
| 91 | Decode ways | Python | O(N) | O(N) | Easy | DP | |
| 1025 | Divisor Game | Python | O(N^2) | O(N) | Easy | DP | |
| 174 | Dungeon Game | C++ | O(M*N) | O(M*N) | Hard | Dynamic Programming | |
| 070 | Climbing Stairs | Java | O(N) | O(1) | Easy | DP | |
| 730 | Count Different Palindromic Subsequences | C++ | O(N*N) | O(N*N) | Hard | DP |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 035 | Search Insert Position | Python | O(logn) | O(1) | Easy | Binary Search | |
| 278 | First Bad Version | Java JavaScript |
O(logn) | O(1) | Easy | Binary Search | |
| 033 | Search in Rotated Sorted Array | Python | O(logn) | O(1) | Medium | Binary Search | |
| 153 | Find Minimum in Rotated Sorted Array | Python | O(logn) | O(1) | Medium | Binary Search | |
| 704 | Binary Search | C++ | O(logn) | O(1) | Easy | Binary Search |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 207 | Course Schedule | C++ | O(V+E) | O(V+E) | Medium | Graph | Cycle Detection in Directed Graph |
| 1042 | Flower Planting with No Adjacent | Python | O(V+E) | O(2V+E) | Medium | Graph | Graph Coloring |
| 797 | All Paths From Source to Target | Java | O(N^2) | O(N) | Medium | Graph | DFS |
1.) Cracking the Coding Interview (Indian Edition)
2.) Data Structures and Algorithms Made Easy in Java
3.) Data Structure and Algorithmic Thinking with Python
4.) Head First Design Patterns
5.) Dynamic Programming for Coding Interviews
DISCLAIMER: This above mentioned resources have affiliate links, which means if you buy one of the product from my links, I’ll receive a small commission. This helps support the channel and allows us to continue to add more tutorial. Thank you for the support!
|