| 395 | Longest Substring with At Least K Repeating Characters | Medium |
| 402 | Remove K Digits | Medium |
| 409 | Longest Palindrome | Easy |
| 420 | Strong Password Checker | Hard |
| 423 | Reconstruct Original Digits from English | Medium |
| 424 | Longest Repeating Character Replacement | Medium |
| 433 | Minimum Genetic Mutation | Medium |
| 434 | Number of Segments in a String | Easy |
| 438 | Find All Anagrams in a String | Medium |
| 443 | String Compression | Medium |
| 449 | Serialize and Deserialize BST | Medium |
| 451 | Sort Characters By Frequency | Medium |
| 459 | Repeated Substring Pattern | Easy |
| 466 | Count The Repetitions | Hard |
| 467 | Unique Substrings in Wraparound String | Medium |
| 468 | Validate IP Address | Medium |
| 472 | Concatenated Words | Hard |
| 474 | Ones and Zeroes | Medium |
| 481 | Magical String | Medium |
| 482 | License Key Formatting | Easy |
| 488 | Zuma Game | Hard |
| 500 | Keyboard Row | Easy |
| 514 | Freedom Trail | Hard |
| 516 | Longest Palindromic Subsequence | Medium |
| 520 | Detect Capital | Easy |
| 521 | Longest Uncommon Subsequence I | Easy |
| 522 | Longest Uncommon Subsequence II | Medium |
| 524 | Longest Word in Dictionary through Deleting | Medium |
| 535 | Encode and Decode TinyURL | Medium |
| 537 | Complex Number Multiplication | Medium |