| 467 | Unique Substrings in Wraparound String | Solution | O(n) | O(1) | Medium | DP | |
| 463 | Island Perimeter | Solution | O(m*n) | O(1) | Easy | | |
| 462 | Minimum Moves to Equal Array Elements II | Solution | O(nlogn) | O(1) | Medium | | |
| 459 | Repeated Substring Pattern | Solution | O(n) | O(n) | Easy | KMP | |
| 456 | 132 Pattern | Solution | O(n) | O(n) | Medium | Stack | |
| 455 | Assign Cookies | Solution | O(n) | O(1) | Easy | | |
| 454 | 4Sum II | Solution | O(n) | O(n) | Medium | HashMap | |
| 453 | Minimum Moves to Equal Array Elements | Solution | O(n) | O(1) | Easy | | |
| 447 | Number of Boomerangs | Solution | O(n^2) | O(n) | Easy | HashMap | |
| 441 | Arranging Coins | Solution | O(n) | O(1) | Easy | | |
| 438 | Find All Anagrams in a String | Solution | O(n) | O(1) | Easy | | |
| 436 | Find Right Interval | Solution | O(nlogn) | O(n) | Medium | Binary Search | |
| 435 | Non-overlapping Intervals | Solution | O(nlogn) | O(1) | Medium | Greedy | |
| 434 | Number of Segments in a String | Solution | O(n) | O(1) | Easy | | |
| 420 | Strong Password Checker | Solution | ? | ? | Hard | | |
| 419 | Battleships in a Board | Solution | O(n^2) | O(1) | Medium | DFS | |
| 417 | Pacific Atlantic Water Flow | Solution | O(mnMax(m,n)) | O(m*n) | Medium | DFS | |
| 415 | Add Strings | Solution | O(n) | O(1) | Easy | | |
| 414 | Third Maximum Number | Solution | O(n) | O(1) | Easy | | |
| 413 | Arithmetic Slices | Solution | O(n) | O(1) | Medium | DP | |
| 412 | Fizz Buzz | Solution | O(n) | O(1) | Easy | | |
| 404 | Sum of Left Leaves | Solution | O(n) | O(h) | Easy | | |
| 398 | Random Pick Index | Solution | | | Medium | Reservoir Sampling | |
| 397 | Integer Replacement | Solution | ? | ? | Easy | BFS | |
| 396 | Rotate Function | Solution | O(n^2) could be optimized to O(n) | O(1) | Easy | | |
| 390 | Elimination Game | Solution | O(logn) | O(1) | Medium | | |
| 389 | Find the Difference | Solution | O(n) | O(1) | Easy | | |
| 388 | Longest Absolute File Path | Solution | O(n) | O(d) | Medium | Stack | |
| 387 | First Unique Character in a String | Solution | O(n) | O(n) | Easy | HashMap | |
| 386 | Lexicographical Numbers | Solution | O(n) | O(1) | Medium | | |
| 379 | Design Phone Directory | Solution | O(1) | O(n) | Medium | | |
| 374 | Guess Number Higher or Lower | Solution | O(logn) | O(1) | Easy | Binary Search | |
| 370 | Range Addition | Solution | O(n+k) | O(1) | Medium | | |
| 366 | Find Leaves of Binary Tree | Solution | O(n) | O(h) | Medium | DFS | |
| 364 | Nested List Weight Sum II | Solution | O(n) | O(h) | Medium | DFS | |
| 362 | Design Hit Counter | Solution | O(1) amortized | O(k) | Medium | Design | |
| 359 | Logger Rate Limiter | Solution | amortized O(1) | O(k) | Easy | HashMap | |
| 350 | Intersection of Two Arrays II | Solution | O(m+n) | O((m+n)) could be optimized | Easy | HashMap, Binary Search | |
| 349 | Intersection of Two Arrays | Solution | O(m+n) | O(min(m,n)) | Easy | Two Pointers, Binary Search | |
| 346 | Moving Average from Data Stream | Solution | O(1) | O(w)) | Easy | Queue | |
| 339 | Nested List Weight Sum | Solution | O(n) | O(h)) | Easy | DFS | |
| 338 | Counting Bits | Solution | O(nlogn) | O(h) | Medium | | |
| 333 | Largest BST Subtree | Solution | O(n) | O(n) | Medium | | |
| 325 | Maximum Size Subarray Sum Equals k | [Solution] | O(n) | O(n) | Medium | HashMap | |
| 314 | Binary Tree Vertical Order Traversal | Solution | O(n) | O(n) | Medium | HashMap, BFS | |
| 311 | Sparse Matrix Multiplication | Solution | O(mnl) | O(m*l) | Medium | | |
| 301 | Remove Invalid Parentheses | [Solution] | ? | ? | Hard | BFS | |
| 299 | Bulls and Cows | Solution | O(n) | O(1) | Easy | | |
| 295 | Find Median from Data Stream | Solution | O(nlogn) | O(n) | Hard | Heap | |
| 293 | Flip Game | Solution | ? | O(n) | Easy | | |
| 292 | Nim Game | Solution | O(1) | O(1) | Easy | | |
| 290 | Word Pattern | Solution | O(n) | O(n) | Easy | | |
| 289 | Game of Life | Solution | O(m*n) | O(m*n), could be optimized to O(1) | Medium | | |
| 288 | Unique Word Abbreviation | Solution | O(n) | O(1) | Easy | | |
| 285 | Inorder Successor In BST | Solution | O(h) | O(1) | Medium | | |
| 283 | Move Zeroes | Solution | O(n) | O(1) | Easy | | |
| 280 | Wiggle Sort | Solution | O(n) | O(1) | Medium | | |
| 278 | First Bad Version | Solution | O(logn) | O(1) | Easy | Binary Search | |
| 276 | Paint Fence | Solution | O(n) | O(1) | Easy | DP | |
| 273 | Integer to English Words | [Solution] | | | | | |
| 270 | Closest Binary Search Tree Value | Solution | O(h) | O(1) | Easy | DFS | |
| 266 | Palindrome Permutation | Solution | O(n) | O(1) | Easy | HashMap | |
| 261 | Graph Valid Tree | Solution | O(V+E) | O(V+E) | Medium | | |
| 259 | 3Sum Smaller | Solution | O(n^2) | O(1) | Medium | | |
| 257 | Binary Tree Paths | Solution | O(n*h) | O(h) | DFS/Recursion | | |
| 252 | Meeting Rooms | Solution | O(nlogn) | O(1) | | | |
| 251 | Flatten 2D Vector | Solution | O(1) | O(m*n) | Medium | | |
| 250 | Count Univalue Subtrees | Solution | O(n) | O(h) | Medium | DFS | |
| 249 | Group Shifted Strings | Solution | O(nlogn) | O(n) | | | |
| 246 | Strobogrammatic Number | Solution | O(n) | O(1) | | | |
| 243 | Shortest Word Distance | Solution | O(n) | O(1) | | | |
| 226 | Invert Binary Tree | Solution | O(n) | O(h) | Easy | DFS, recursion | |
| 223 | Rectangle Area | Solution | O(1) | O(1) | Easy | | |
| 219 | Contains Duplicate II | Solution | O(n) | O(n) | Easy | HashMap | |
| 209 | Minimum Size Subarray Sum | Solution | O(n) | O(1) | Medium | | |
| 208 | Implement Trie | Solution | O(n) | O(1) | Medium | | |
| 206 | Reverse Linked List | Solution | O(n) | O(1) | Easy | | |
| 205 | Isomorphic Strings | Solution | O(n) | O(1) | Easy | | |
| 200 | Number of Islands | Union FindDFS | O(m*n) | O(m*n) | Medium | Union Find, DFS | |
| 189 | Rotate Array | Solution | O(n) | O(n), could be optimized to O(1) | Easy | | |
| 182 | Duplicate Emails | Solution | O(n^2) | O(n) | Easy | | |
| 173 | Binary Search Tree Iterator | QueueStack | O(1) | O(h) | Medium | | |
| 172 | Factorial Trailing Zeroes | Solution | O(logn) | O(1) | Easy | | |
| 170 | Two Sum III - Data structure design | Solution | O(n) | O(n) | Easy | | |
| 169 | Majority Element | Solution | O(n) | O(1) | Easy | | |
| 165 | Compare Version Numbers | Solution | O(n) | O(1) | Easy | | |
| 162 | Find Peak Element | Solution | O(1) | O(logn)/O(n) | Binary Search | | |
| 161 | One Edit Distance | Solution | O(n) | O(1) | | | |
| 160 | Intersection of Two Linked Lists | Solution | O(m+n) | O(1) | Easy | Linked List | |
| 157 | Read N Characters Given Read4 | Solution | O(n) | O(1) | Easy | | |
| 155 | Min Stack | Solution | O(1) | O(n) | Easy | Stack | |
| 151 | Reverse Words in a String | Solution | O(n) | O(n) | Medium | | |
| 142 | Linked List Cycle II | Solution | O(n) | O(1) | Medium | Linked List | |
| 141 | Linked List Cycle | Solution | O(n) | O(1) | Easy | Linked List | |
| 140 | Word Break II | Solution | ? | O(n^2) | Hard | Backtracking/DFS | |
| 139 | Word Break | Solution | O(n^2) | O(n) | Medium | DP | |
| 133 | Clone Graph | Solution | O(n) | O(n) | Medium | HashMap, BFS | |
| 125 | Valid Palindrome | Solution | O(n) | O(1) | Easy | Two Pointers | |
| 122 | Best Time to Buy and Sell Stock II | Solution | O(n) | O(1) | Medium | Greedy | |
| 121 | Best Time to Buy and Sell Stock | Solution | O(n) | O(1) | Easy | DP | |
| 120 | Triangle | Solution | O(m*n) | O(n) | Medium | DP | |
| 119 | Pascal's Triangle II | Solution | O(n^2) | O(1) | Easy | | |
| 118 | Pascal's Triangle | Solution | O(n^2) | O(1) | Easy | | |
| 117 | Populating Next Right Pointers in Each Node II | Solution | O(n) | O(1) | Hard | BFS | |
| 116 | Populating Next Right Pointers in Each Node | Solution | O(n) | O(1) | Medium | BFS | |
| 112 | Path Sum | Solution | O(n) | O(1) | Easy | DFS | |
| 111 | Minimum Depth of Binary Tree | Solution | O(n) | O(1)~O(h) | Easy | BFS, DFS | |
| 91 | Decode Ways | Solution | O(n) | O(n) | Medium | DP | |
| 98 | Validate Binary Search Tree | [Solution] | O(n) | O(1) | Medium | DFS/Recursion | |
| 79 | Word Search | Solution | O(mnl) ? | O(m*n) | Medium | Backtracking/DFS | |
| 78 | Subsets | Solution | O(n^2) ? | O(1) | Medium | Backtracking | |
| 76 | Minimum Window Substring | Solution | O(n) | O(k) | Hard | Two Pointers | |
| 75 | Sort Colors | Solution | O(n) | O(1) | Medium | Two Pointers | |
| 73 | Set Matrix Zeroes | Solution | O(mn) | O(mn) | Medium | | |
| 68 | Text Justification | Solution | O(n) | O(1) | Hard | | |
| 67 | Add Binary | Solution | O(n) | O(1) | Easy | | |
| 58 | Length of Last Word | Solution | O(n) | O(1) | Easy | | |
| 56 | Merge Intervals | Solution | O(n*logn) | O(1) | Hard | | |
| 47 | Permutations II | Solution | O(n*n!) | O(n) | Medium | Backtracking | |
| 43 | Multiply Strings | [Solution] | | | Medium | | |
| 39 | Combination Sum | Solution | O(k*n^k) | O(k) | Medium | Backtracking | |
| 31 | Next Permutation | Solution | O(n) | O(1) | Medium | Array | |
| 24 | Swap Nodes in Pairs | Solution | O(n) | O(1) | Easy | Recursion, LinkedList | |
| 23 | Merge k Sorted Lists | Solution | O(n*logk) | O(logk) | Hard | Heap | |
| 22 | Generate Parentheses | Solution | TBD | O(n) | Medium | Backtracking | |
| 21 | Merge Two Sorted Lists | Solution | O(n) | O(1) | Easy | | |
| 20 | Valid Parentheses | Solution | O(n) | O(n) | Easy | Stack | |
| 17 | Letter Combinations of a Phone Number | Solution | O(n*4^n) | O(n) | Medium | Backtracking | |
| 15 | 3Sum | Solution | O(n^2) | O(1) | Medium | Two Pointers | |
| 14 | Longest Common Prefix | Solution | O(n*min(wordLength in this array)) | O(1) | Easy | | |
| 13 | Roman to Integer | Solution | O(1) | O(1) | Easy | | |
| 12 | Integer to Roman | Solution | O(1) | O(1) | Medium | | |
| 10 | Regular Expression Matching | Solution | O(m*n) | O(m*n) | Hard | DP | |
| 9 | Palindrome Number | Solution | O(logn)/(n) | O(1) | Easy | | |
| 8 | String to Integer (atoi) | Solution | O(n) | O(1) | Easy | | |
| 7 | Reverse Integer | Solution | O(1) | O(1) | Easy | | |
| 6 | ZigZag Conversion | Solution | O(n) | O(n) | Easy | | |
| 3 | Longest Substring Without Repeating Characters | Solution | O(n) | O(1) | Medium | HashMap, Sliding Window | |
| 2 | Add Two Numbers | Solution | O(n) | O(1) | Medium | LinkedList | |
| 1 | Two Sum | Solution | O(n)/O(n^2) | O(1)/O(n) | Easy | HashMap | |