| # | title | topic | type | difficulty |
|---|---|---|---|---|
| 1 | Depth-first search: recursive traversal | Algorithms & Recursion | Coding | Medium |
| 2 | The same check, in one pass of methods | Algorithms & Recursion | Coding | Medium |
| 3 | The same prefix, without shrinking a guess | Algorithms & Recursion | Coding | Medium |