###LeetCode Algorithm
(Notes: "♥" means you need to buy a book from Leetcode)
| # | Title | Solution | Difficulty |
|---|---|---|---|
| 23 | Merge k Sorted Lists | C++ | Hard |
| 22 | Generate Parentheses | C++ | Easy |
| 21 | Merge Two Sorted Lists | C++ | Easy |
| 20 | Valid Parentheses | C++ | Easy |
| 19 | Remove Nth Node From End Of List | C++ | Easy |
| 18 | 4Sum | C++ | Medium |
| 17 | Letter Combinations of a Phone Number | C++ | Medium |
| 16 | 3Sum Closest | C++ | Medium |
| 15 | 3Sum | C++ | Medium |
| 14 | Longest Common Prefix | C++ | Easy |
| 9 | Palindrome Number | C++ | Easy |
| 8 | String to Integer (atoi) | C++ | Easy |
| 7 | Reverse Integer | C++ | Easy |
| 6 | ZigZag Conversion | C++ | Easy |
| 5 | Longest Palindromic Substring | C++ | Medium |
| 3 | Longest Substring Without Repeating Characters | C++ | Medium |
| 2 | Add Two Numbers | C++ | Medium |
| 1 | Two Sum | C++ | Medium |