| # | Title | Difficulty |
|---|---|---|
| 1 | Two Sum | Easy |
| 7 | Reverse Integer | Easy |
| 9 | Palindrome Number | Easy |
| 14 | Longest Common Prefix | Easy |
| 20 | Valid Parentheses | Easy |
| 26 | Remove Duplicates from Sorted Array | Easy |
| 27 | Remove Element | Easy |
| 35 | Search Insert Position | Easy |
| 66 | Plus One | Easy |
| 88 | Merge Sorted Array | Easy |
| 136 | Single Number | Easy |
| 167 | Two Sum II | Easy |
| 169 | Majority Element | Easy |
| 189 | Rotate Array | Easy |
| 202 | Happy Number | Easy |
| 204 | Count Primes | Easy |
| 205 | Isomorphic Strings | Easy |
| 217 | Contains Duplicate | Easy |
| 242 | Valid Anagram | Easy |
| 290 | World Pattern | Easy |