| Problem | Difficulty |
|---|---|
| 146. LRU Cache | Medium |
| 295. Find Median from Data Stream | Hard |
| 1472. Design Browser History | Medium |
| 706. Design HashMap | Easy |
| 705. Design HashSet | Easy |
| 173. Binary Search Tree Iterator | Medium |
| 380. Insert Delete GetRandom O(1) | Medium |
| 341. Flatten Nested List Iterator | Medium |
| 729. My Calendar I | Medium |
| 981. Time Based Key-Value Store | Medium |