| # | title | topic | type | difficulty |
|---|---|---|---|---|
| 1 | LRU cache with O(1) operations | Interview Classics | Coding | Hard |
| 2 | Build an EventEmitter | Interview Classics | Coding | Hard |
| 3 | Longest substring without repeats (sliding window) | Interview Classics | Coding | Hard |
| 4 | Flatten an object to dot-paths (and holes beware) | Interview Classics | Coding | Hard |
| 5 |
| Trapping rain water (two pointers) |
| Interview Classics |
| Coding |
| Hard |
| 6 | Edit distance (Levenshtein, full DP) | Interview Classics | Coding | Hard |
| 7 | deepClone that preserves cycles | Interview Classics | Coding | Hard |
| 8 | All permutations, in order | Interview Classics | Coding | Hard |