| 2 | Add Two Numbers | Medium |
| 7 | Reverse Integer | Easy |
| 8 | String to Integer (atoi) | Medium |
| 9 | Palindrome Number | Easy |
| 12 | Integer to Roman | Medium |
| 13 | Roman to Integer | Easy |
| 29 | Divide Two Integers | Medium |
| 43 | Multiply Strings | Medium |
| 50 | Pow(x, n) | Medium |
| 60 | Permutation Sequence | Medium |
| 65 | Valid Number | Hard |
| 66 | Plus One | Easy |
| 67 | Add Binary | Easy |
| 69 | Sqrt(x) | Easy |
| 149 | Max Points on a Line | Hard |
| 166 | Fraction to Recurring Decimal | Medium |
| 168 | Excel Sheet Column Title | Easy |
| 171 | Excel Sheet Column Number | Easy |
| 172 | Factorial Trailing Zeroes | Easy |
| 202 | Happy Number | Easy |
| 204 | Count Primes | Medium |
| 223 | Rectangle Area | Medium |
| 224 | Basic Calculator | Hard |
| 227 | Basic Calculator II | Medium |
| 231 | Power of Two | Easy |
| 233 | Number of Digit One | Hard |
| 241 | Different Ways to Add Parentheses | Medium |
| 258 | Add Digits | Easy |
| 263 | Ugly Number | Easy |
| 264 | Ugly Number II | Medium |