| 208 | Implement Trie (Prefix Tree) | Medium |
| 211 | Design Add and Search Words Data Structure | Medium |
| 336 | Palindrome Pairs | Hard |
| 386 | Lexicographical Numbers | Medium |
| 421 | Maximum XOR of Two Numbers in an Array | Medium |
| 440 | K-th Smallest in Lexicographical Order | Hard |
| 472 | Concatenated Words | Hard |
| 648 | Replace Words | Medium |
| 676 | Implement Magic Dictionary | Medium |
| 677 | Map Sum Pairs | Medium |
| 692 | Top K Frequent Words | Medium |
| 720 | Longest Word in Dictionary | Medium |
| 745 | Prefix and Suffix Search | Hard |
| 792 | Number of Matching Subsequences | Medium |
| 820 | Short Encoding of Words | Medium |
| 1023 | Camelcase Matching | Medium |
| 1032 | Stream of Characters | Hard |
| 1178 | Number of Valid Words for Each Puzzle | Hard |
| 1233 | Remove Sub-Folders from the Filesystem | Medium |
| 1268 | Search Suggestions System | Medium |
| 1316 | Distinct Echo Substrings | Hard |
| 1707 | Maximum XOR With an Element From Array | Hard |
| 1803 | Count Pairs With XOR in a Range | Hard |
| 1938 | Maximum Genetic Difference Query | Hard |
| 1948 | Delete Duplicate Folders in System | Hard |
| 2227 | Encrypt and Decrypt Strings | Hard |
| 2261 | K Divisible Elements Subarrays | Medium |
| 2707 | Extra Characters in a String | Medium |