| 146 | LRU Cache | Hard |
| 155 | Min Stack | Easy |
| 173 | Binary Search Tree Iterator | Medium |
| 208 | Implement Trie (Prefix Tree) | Medium |
| 232 | Implement Queue using Stacks | Easy |
| 295 | Find Median from Data Stream | Hard |
| 303 | Range Sum Query - Immutable | Easy |
| 304 | Range Sum Query 2D - Immutable | Medium |
| 341 | Flatten Nested List Iterator | Medium |
| 380 | Insert Delete GetRandom O(1) | Medium |
| 381 | Insert Delete GetRandom O(1) - Duplicates allowed | Hard |
| 706 | Design HashMap | Easy |
| 1845 | Seat Reservation Manager | Medium |
| 2353 | Design a Food Rating System | Medium |
| 2642 | Design Graph With Shortest Path Calculator | Hard |