| 1143 | Longest Common Subsequence | Medium |
| 1154 | Day of the Year | Easy |
| 1156 | Swap For Longest Repeated Character Substring | Medium |
| 1160 | Find Words That Can Be Formed by Characters | Easy |
| 1163 | Last Substring in Lexicographical Order | Hard |
| 1169 | Invalid Transactions | Medium |
| 1170 | Compare Strings by Frequency of the Smallest Character | Medium |
| 1177 | Can Make Palindrome from Substring | Medium |
| 1178 | Number of Valid Words for Each Puzzle | Hard |
| 1189 | Maximum Number of Balloons | Easy |
| 1190 | Reverse Substrings Between Each Pair of Parentheses | Medium |
| 1202 | Smallest String With Swaps | Medium |
| 1208 | Get Equal Substrings Within Budget | Medium |
| 1209 | Remove All Adjacent Duplicates in String II | Medium |
| 1221 | Split a String in Balanced Strings | Easy |
| 1233 | Remove Sub-Folders from the Filesystem | Medium |
| 1234 | Replace the Substring for Balanced String | Medium |
| 1239 | Maximum Length of a Concatenated String with Unique Characters | Medium |
| 1247 | Minimum Swaps to Make Strings Equal | Medium |
| 1249 | Minimum Remove to Make Valid Parentheses | Medium |
| 1251 | Longest Chunked Palindrome Decomposition | Hard |
| 1255 | Maximum Score Words Formed by Letters | Hard |
| 1268 | Search Suggestions System | Medium |
| 1278 | Palindrome Partitioning III | Hard |
| 1286 | Iterator for Combination | Medium |
| 1297 | Maximum Number of Occurrences of a Substring | Medium |
| 1307 | Verbal Arithmetic Puzzle | Hard |
| 1309 | Decrypt String from Alphabet to Integer Mapping | Easy |
| 1312 | Minimum Insertion Steps to Make a String Palindrome | Hard |
| 1316 | Distinct Echo Substrings | Hard |