| 146. LRU Cache | | | Solve | Medium | | |
| 155. Min Stack | | | Solve | Medium | | |
| 173. Binary Search Tree Iterator | | | Solve | Medium | | |
| 208. Implement Trie (Prefix Tree) | | | Solve | Medium | | |
| 211. Design Add and Search Words Data Structure | | | Solve | Medium | | |
| 244. Shortest Word Distance II | | | Solve | Medium | | |
| 251. Flatten 2D Vector | | | Solve | Medium | | |
| 271. Encode and Decode Strings | | | Solve | Medium | | |
| 281. Zigzag Iterator | | | Solve | Medium | | |
| 284. Peeking Iterator | | | Solve | Medium | | |
| 288. Unique Word Abbreviation | | | Solve | Medium | | |
| 304. Range Sum Query 2D - Immutable | | | Solve | Medium | | |
| 307. Range Sum Query - Mutable | | | Solve | Medium | | |
| 308. Range Sum Query 2D - Mutable | | | Solve | Medium | | |
| 341. Flatten Nested List Iterator | | | Solve | Medium | | |
| 348. Design Tic-Tac-Toe | | | Solve | Medium | | |
| 353. Design Snake Game | | | Solve | Medium | | |
| 355. Design Twitter | | | Solve | Medium | | |
| 362. Design Hit Counter | | | Solve | Medium | | |
| 379. Design Phone Directory | | | Solve | Medium | | |
| 380. Insert Delete GetRandom O(1) | | | Solve | Medium | | |
| 384. Shuffle an Array | | | Solve | Medium | | |
| 449. Serialize and Deserialize BST | | | Solve | Medium | | |
| 535. Encode and Decode TinyURL | | | Solve | Medium | | |
| 622. Design Circular Queue | | | Solve | Medium | | |
| 635. Design Log Storage System | | | Solve | Medium | | |
| 641. Design Circular Deque | | | Solve | Medium | - | |
| 676. Implement Magic Dictionary | | | Solve | Medium | | |
| 677. Map Sum Pairs | | | Solve | Medium | | |
| 707. Design Linked List | | | Solve | Medium | | |
| 729. My Calendar I | | | Solve | Medium | | |
| 731. My Calendar II | | | Solve | Medium | | |
| 855. Exam Room | | | Solve | Medium | | |
| 900. RLE Iterator | | | Solve | Medium | | |
| 901. Online Stock Span | | | Solve | Medium | | |
| 911. Online Election | | | Solve | Medium | | |
| 919. Complete Binary Tree Inserter | | | Solve | Medium | | |
| 981. Time Based Key-Value Store | | | Solve | Medium | | |
| 1146. Snapshot Array | | | Solve | Medium | | |
| 1166. Design File System | | | Solve | Medium | | |
| 1244. Design A Leaderboard | | | Solve | Medium | | |
| 1261. Find Elements in a Contaminated Binary Tree | | | Solve | Medium | | |
| 1286. Iterator for Combination | | | Solve | Medium | | |
| 1348. Tweet Counts Per Frequency | | | Solve | Medium | | |
| 1352. Product of the Last K Numbers | | | Solve | Medium | | |
| 1357. Apply Discount Every n Orders | | | Solve | Medium | | |
| 1381. Design a Stack With Increment Operation | | | Solve | Medium | | |
| 1396. Design Underground System | | | Solve | Medium | | |
| 1429. First Unique Number | | | Solve | Medium | | |
| 1472. Design Browser History | | | Solve | Medium | | |
