| 156. Binary Tree Upside Down | Solution | Solve | Medium | | |
| 159. Longest Substring with At Most Two Distinct Characters | Solution | Solve | Medium | | |
| 161. One Edit Distance | Solution | Solve | Medium | | |
| 186. Reverse Words in a String II | Solution | Solve | Medium | | |
| 244. Shortest Word Distance II | Solution | Solve | Medium | | |
| 245. Shortest Word Distance III | Solution | Solve | Medium | | |
| 247. Strobogrammatic Number II | Solution | Solve | Medium | | |
| 249. Group Shifted Strings | Solution | Solve | Medium | | |
| 250. Count Univalue Subtrees | Solution | Solve | Medium | | |
| 251. Flatten 2D Vector | Solution | Solve | Medium | | |
| 253. Meeting Rooms II | Solution | Solve | Medium | | |
| 254. Factor Combinations | Solution | Solve | Medium | | |
| 255. Verify Preorder Sequence in Binary Search Tree | Solution | Solve | Medium | | |
| 256. Paint House | Solution | Solve | Medium | | |
| 259. 3Sum Smaller | Solution | Solve | Medium | | |
| 261. Graph Valid Tree | Solution | Solve | Medium | | |
| 267. Palindrome Permutation II | Solution | Solve | Medium | | |
| 271. Encode and Decode Strings | Solution | Solve | Medium | | |
| 276. Paint Fence | Solution | Solve | Medium | | |
| 277. Find the Celebrity | Solution | Solve | Medium | | |
| 280. Wiggle Sort | Solution | Solve | Medium | | |
| 281. Zigzag Iterator | Solution | Solve | Medium | | |
| 285. Inorder Successor in BST | Solution | Solve | Medium | | |
| 286. Walls and Gates | Solution | Solve | Medium | | |
| 288. Unique Word Abbreviation | Solution | Solve | Medium | | |
| 291. Word Pattern II | Solution | Solve | Medium | | |
| 294. Flip Game II | Solution | Solve | Medium | | |
| 298. Binary Tree Longest Consecutive Sequence | Solution | Solve | Medium | | |
| 308. Range Sum Query 2D - Mutable | Solution | Solve | Medium | | |
| 311. Sparse Matrix Multiplication | Solution | Solve | Medium | | |
| 314. Binary Tree Vertical Order Traversal | Solution | Solve | Medium | | |
| 320. Generalized Abbreviation | Solution | Solve | Medium | | |
| 323. Number of Connected Components in an Undirected Graph | Solution | Solve | Medium | | |
| 325. Maximum Size Subarray Sum Equals k | Solution | Solve | Medium | | |
| 333. Largest BST Subtree | Solution | Solve | Medium | | |
| 339. Nested List Weight Sum | Solution | Solve | Medium | | |
| 340. Longest Substring with At Most K Distinct Characters | Solution | Solve | Medium | | |
| 348. Design Tic-Tac-Toe | Solution | Solve | Medium | | |
| 351. Android Unlock Patterns | Solution | Solve | Medium | | |
| 353. Design Snake Game | Solution | Solve | Medium | | |
| 356. Line Reflection | Solution | Solve | Medium | | |
| 360. Sort Transformed Array | Solution | Solve | Medium | | |
| 361. Bomb Enemy | Solution | Solve | Medium | | |
| 362. Design Hit Counter | Solution | Solve | Medium | | |
| 364. Nested List Weight Sum II | Solution | Solve | Medium | | |
| 366. Find Leaves of Binary Tree | Solution | Solve | Medium | | |
| 369. Plus One Linked List | Solution | Solve | Medium | | |
| 370. Range Addition | Solution | Solve | Medium | | |
| 379. Design Phone Directory | Solution | Solve | Medium | | |
| 418. Sentence Screen Fitting | Solution | Solve | Medium | | |
