| 14 | Longest Common Prefix | — | Easy | StringTrie | 45% | |
| 139 | Word Break | — | Medium | ArrayHash TableString | 48% | |
| 140 | Word Break II | — | Hard | ArrayHash TableString | 53% | |
| 208 | Implement Trie (Prefix Tree)read | — | Medium | Hash TableStringDesign | 68% | |
| 211 | Design Add and Search Words Data Structureread | — | Medium | StringDepth-First SearchDesign | 47% | |
| 212 | Word Search II | — | Hard | ArrayStringBacktracking | 37% | |
| 336 | Palindrome Pairs | — | Hard | ArrayHash TableString | 36% | |
| 386 | Lexicographical Numbersread | — | Medium | Depth-First SearchTrie | 73% | |
| 421 | Maximum XOR of Two Numbers in an Arrayread | — | Medium | ArrayHash TableBit Manipulation | 53% | |
| 440 | K-th Smallest in Lexicographical Orderread | — | Hard | Trie | 42% | |
| 472 | Concatenated Words | — | Hard | ArrayStringDynamic Programming | 49% | |
| 648 | Replace Wordsread | — | Medium | ArrayHash TableString | 68% | |
| 676 | Implement Magic Dictionaryread | — | Medium | Hash TableStringDepth-First Search | 57% | |
| 677 | Map Sum Pairsread | — | Medium | Hash TableStringDesign | 57% | |
| 692 | Top K Frequent Words | — | Medium | ArrayHash TableString | 59% | |
| 720 | Longest Word in Dictionary | — | Medium | ArrayHash TableString | 53% | |
| 745 | Prefix and Suffix Searchread | — | Hard | ArrayHash TableString | 40% | |
| 792 | Number of Matching Subsequences | — | Medium | ArrayHash TableString | 51% | |
| 820 | Short Encoding of Words | — | Medium | ArrayHash TableString | 61% | |
| 1023 | Camelcase Matching | — | Medium | ArrayTwo PointersString | 64% | |
| 1032 | Stream of Charactersread | — | Hard | ArrayStringDesign | 51% | |
| 1178 | Number of Valid Words for Each Puzzle | — | Hard | ArrayHash TableString | 47% | |
| 1233 | Remove Sub-Folders from the Filesystem | — | Medium | ArrayStringDepth-First Search | 76% | |
| 1268 | Search Suggestions Systemread | — | Medium | ArrayStringBinary Search | 65% | |
| 1316 | Distinct Echo Substrings | — | Hard | StringTrieRolling Hash | 52% | |
| 1707 | Maximum XOR With an Element From Arrayread | — | Hard | ArrayBit ManipulationTrie | 54% | |
| 1803 | Count Pairs With XOR in a Rangeread | — | Hard | ArrayBit ManipulationTrie | 46% | |
| 1938 | Maximum Genetic Difference Queryread | — | Hard | ArrayHash TableBit Manipulation | 44% | |
| 1948 | Delete Duplicate Folders in Systemread | — | Hard | ArrayHash TableString | 54% | |
| 2227 | Encrypt and Decrypt Stringsread | — | Hard | ArrayHash TableString | 37% | |
| 2261 | K Divisible Elements Subarraysread | — | Medium | ArrayHash TableTrie | 54% | |
| 2416 | Sum of Prefix Scores of Strings | — | Hard | ArrayStringTrie | 61% | |
| 2452 | Words Within Two Edits of Dictionary | — | Medium | ArrayStringTrie | 61% | |
| 2707 | Extra Characters in a Stringread | — | Medium | ArrayHash TableString | 57% | |
| 2932 | Maximum Strong Pair XOR Iread | — | Easy | ArrayHash TableBit Manipulation | 75% | |
| 2935 | Maximum Strong Pair XOR IIread | — | Hard | ArrayHash TableBit Manipulation | 31% | |
| 2977 | Minimum Cost to Convert String IIread | — | Hard | ArrayStringDynamic Programming | 25% | |
| 3042 | Count Prefix and Suffix Pairs I | — | Easy | ArrayStringTrie | 78% | |
| 3043 | Find the Length of the Longest Common Prefix | — | Medium | ArrayHash TableString | 56% | |
| 3045 | Count Prefix and Suffix Pairs II | — | Hard | ArrayStringTrie | 27% | |
| 3076 | Shortest Uncommon Substring in an Array | — | Medium | ArrayHash TableString | 48% | |
| 3093 | Longest Common Suffix Queries | — | Hard | ArrayStringTrie | 37% | |
| 3291 | Minimum Number of Valid Strings to Form Target Iread | — | Medium | ArrayStringBinary Search | 20% | |
| 3485 | Longest Common Prefix of K Strings After Removalread | — | Hard | ArrayStringTrie | 20% | |