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Algorithms
- 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
Bit Manipulation
| # | Title | Solution | Time | Space | Difficulty | Tag | Tutorial |
|---|---|---|---|---|---|---|---|
| 136 | Single Number | Java Python C++ JavaScript |
O(n) | O(1) | Easy | Using XOR | |
| 137 | Single Number II | Python C++ |
O(n) | O(1) | Medium | ||
| 260 | Single Number III | Python C++ |
O(n) | O(1) | Medium | ||
| 371 | Sum of Two Integers | Java | O(1) | O(1) | Medium | ||
| 476 | Number Complement | Java C++ |
O(1) | O(1) | Easy | Tutorial | |
| 520 | Detect Capital Use | Python C++ |
O(n) | O(1) | Easy | ||
| 1486 | XOR Operation in an Array | Java C++ |
O(n) | O(1) | Easy | Using XOR |
Sort
| # | Title | Solution | Time | Space | Difficulty | Tag | Tutorial |
|---|---|---|---|---|---|---|---|
| 973 | K Closest Points to Origin | C++ | O(n) | O(1) | Medium |
Array
| # | Title | Solution | Time | Space | Difficulty | Note | Video Explaination |
|---|---|---|---|---|---|---|---|
| 118 | Pascal's Triangle | Java | O(N^2) | O(N) | Easy | ||
| 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 | |
| 189 | Rotate-Array | Python | O(N) | O(1) | Medium | Array | |
| 496 | next-greater-element-i | Python | O(N) | O(1) | Medium | Array | |
| 1470 | Shuffle the Array | Java | O(N) | O(1) | Easy | Array | |
| 124 | Permutation by Recussion | Java | O(N) | O(N) | Easy | Array | |
| 283 | Move-Zeroes | C++ | O(N) | O(1) | Easy | Array | |
| 27 | Remove-Element | C++ | O(N) | O(1) | Easy | Array | |
| 36 | Valid Sudoku | Java | O(N^2) | O(N) | Medium | Array, 2D Matrix | |
| 1512 | Number of Good Pairs | Java | O(N^2) | O(1) | Easy | Array | |
| 162 | Find Peak element | javascript | o(Logn) | O(1) | Medium | Array | |
| 54 | Spiral Matrix | C++ | O(M*N) | O(M*N) | Medium | Array | |
| 238 | Product of Array Except Self | C++ | O(N) | O(N) | Medium | Array |
String
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 3 | Longest Substring Without Repeating Characters | Python | O(n) | O(n) | Medium | Hash TableSliding Window |
Open for improvisation, mentioned time and space complexities unconfirmed |
| 8 | String to Integer (atoi) | Java | O(n) | O(1) | Medium | ||
| 9 | Palindrome Number | Java | O(n) | O(1) | Easy | ||
| 151 | Reverse Words in a String | Java | O(1) | O(n) | Medium | ||
| 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 | |
| 520 | Detect Capital Use | Java | O(n) | O(1) | Easy | ||
| 767 | Reorganize String | Python | O(n) | O(n) | Medium | ||
| 859 | Buddy Strings | Java | O(n) | O(1) | Easy | ||
| 1221 | Split a String in Balanced Strings | Python | O(n) | O(1) | Easy | ||
| 1374 | Generate a String With Characters That Have Odd Counts | Java | O(n) | O(1) | Easy | ||
| 1614 | Maximum Nesting Depth of the Parentheses | Java | O(n) | O(1) | Easy |
Linked List
| # | Title | Solution | Time | Space | Difficulty | Tag | Tutorial |
|---|---|---|---|---|---|---|---|
| 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 | |
| 23 | Merge K sorted lists | C++ | O(nlogn) | O(n) | Hard | sorting and append | |
| 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++ Python |
O(1) | O(k) | Medium | Hash Map | |
| 160 | Intersection of Two Linked Lists | Java | O(n) | O(1) | Easy | Two Pointers | Tutorial |
| 186 | Middle of the Linked List | Java | O(n) | O(1) | Easy | Two pointers | |
| 143 | Reorder List | C++ | O(n) | O(n) | Medium | Iteration and Stack | |
| 24 | Swap Nodes in Pairs | C++ | O(n) | O(1) | Medium | Two pointers |
Stack
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 020 | Valid Parentheses | Python C++Java | O(n) | O(n) | Easy | Stack | |
| 084 | Largest Rectangle in Histogram | C++ | O(n) | O(n) | Hard | Stack | |
| 150 | Evaluate Reverse Polish Notation | Python Java |
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 | |
| 94 | Binary Tree Inorder Traversal | Python | O(n) | O(n) | Medium | Recursion, Binary Tree | |
| 735 | Asteroid Collision | C++ | O(n) | O(1) | Medium | Stack | |
| 394 | Decode String | C++ | O(n) | O(1) | Medium | Stack | |
| 921 | Minimum Add to Make Parentheses Valid | C++ | O(n) | O(1) | Medium | Stack | |
| 32 | Longest Valid Parentheses | Python | O(n) | O(n) | Hard | Stack | |
| 1249 | Minimum Remove to Make Valid Parentheses | C++ | O(n) | O(n) | Medium | Stack |
Queue
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 933 | Number of Recent Calls | C++ | O(1) | O(1) | Easy | Queue, Sliding Window | |
| 641 | Design Circular Deque | Java | O(n) | O(n) | Medium | Queue, Design | |
| 621 | Task Scheduler | Python | O(n) | O(n) | Medium | Queue | |
| 622 | Design Circular Queue | Python | O(n) | O(n) | Medium | Queue |
Tree
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 094 | Binary Tree Inorder Traversal | Java Python |
O(n) | O(logn) | Medium | Binary Tree, Stack, HashTable | |
| 100 | Same Tree | Python Java |
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 | |
| 684 | Redundant Connection | Java | O(N) | O(N) | Medium | Tree, Union Find | |
| 102 | Binary Tree Level Order Traversal | C++ | O(n) | O(n) | Medium | Binary Tree, map |
Hash Table
| # | 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 | ||
| 389 | Find The Difference | C++ | O(n) | O(1) | Easy |
Two Pointers
| # | 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 | |
| 015 | 3 Sum | C++ | O(N) | O(1) | Medium | Two Pointer | |
| 021 | Merge Two Sorted Lists | C++ | O(N) | O(1) | Easy | Two Pointer |
Math
| # | 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 | |
| 171 | Excel Sheet Column Number | C++ | O(n) | O(1) | Easy | String | |
| 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 C++ |
O(n) | O(1) | Easy | Math | |
| 14 | Arithmetic Subarrays | Java | O(m*n) | O(n) | Medium | Math | Pattern Count |
| 263 | Ugly Number | Java | O(n) | O(n) | Easy | Math | |
| 412 | Fizz Buzz | Java | O(n) | O(n) | Easy | Math | |
| 1518 | Water Bottles | Java | O(n) | O(n) | Easy | Math | |
| 1822 | Sign Of Product | Java | O(n) | O(n) | Easy | Math | |
| 991 | Broken Calculator | Java | O(n) | O(n) | Medium | Math | |
| 1837 | Sum of Digits in Base K | Python | O(n) | O(1) | Easy | Math |
Breadth-First Search
| # | 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 | |
| 743 | Network Delay Time | C++ | O(V+E)) | O(V) | Medium | BFS | |
| 111 | Min Depth of Binary Tree | JavaScript | O(nlogn) | O(nlogn) | Easy | BFS | |
| 100 | Same Tree | C++ | O(N) | O(N) | Easy | BFS |
Depth-First Search
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 1463 | Cherry Pickup II | C++ | O(n * m) | O(n * m) | Hard | DFS | |
| 104 | Maximum Depth of Binary Tree | python | O(n) | O(n) | Easy | DFS | |
| 112 | Path Sum | Java | O(n) | O(n) | Easy | DFS | |
| 110 | Balanced Binary Tree | Java | O(n) | O(n) | Easy | DFS | |
| 1376 | Time Needed to Inform All Employees | C++ | O(n) | O(n) | Medium | DFS | |
| 200 | Number of Islands | C++ | O(m * n) | O(m * n) | Medium | DFS |
BackTracking
| # | 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 | |
| 17 | Letter Combinations of a Phone Number | C++ | O(4^n) | O(n) | Medium | String, Hash Table, Backtracking |
Dynamic Programming
| # | 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 | |
| 55 | Jump Game | Python | O(N) | O(N) | Medium | DP |
Binary Search
| # | 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 |
Graph
| # | 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 |
| 934 | Shortest Bridge | C++ | O(V) | O(V) | Medium | Graph | DFS + BFS |
| 1192 | Critical Connections in a Network | C++ | O(V+E) | O(4V+E) | Hard | Graph | Tarjan's Algorithm |
| 113 | Path Sum II | C++ | O(V+E) | O(V) | Medium | Graph | DFS |
| 785 | Is Graph Bipartite? | C++ | O(V+E) | O(V) | Medium | Graph | BFS |
| 947 | Most Stones Removed with Same Row or Column | C++ | O(V) | O(2V) | Medium | Graph | Union Find |
| 210 | Course Schedule II | C++ | O(V+E) | O(V) | Medium | Graph | BFS |
| 1627 | Graph Connectivity with Threshold | Java | O(V.logV + Q) | O(V) | Hard | Graph | Union Find + Sieve |
| 1631 | Path with Minimum Effort | Java | O(V^2) | O(V) | Medium | Graph | Dijkstra's Shortest Path |
Learning Resources
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
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