# String

- [Longest Substring Without Repeating Characters](/algo/string/longest-substring-without-repeating-characters.md): ID: 3; medium
- [Roman to Integer](/algo/string/roman-to-integer.md): ID: 13; easy
- [Implement strStr()](/algo/string/implement-strstr.md): ID: 28; easy
- [Reverse Words in a String](/algo/string/reverse-words-in-a-string.md): ID: 151; medium
- [First Unique Character in a String](/algo/string/first-unique-character-in-a-string.md): ID: 209; easy
- [Count Unique Characters of All Substrings of a Given String](/algo/string/count-unique-characters-of-all-substrings-of-a-given-string.md): ID: 828; hard