| 648 | Replace Words | Medium |
| 649 | Dota2 Senate | Medium |
| 650 | 2 Keys Keyboard | Medium |
| 652 | Find Duplicate Subtrees | Medium |
| 653 | Two Sum IV - Input is a BST | Easy |
| 654 | Maximum Binary Tree | Medium |
| 655 | Print Binary Tree | Medium |
| 657 | Robot Return to Origin | Easy |
| 658 | Find K Closest Elements | Medium |
| 659 | Split Array into Consecutive Subsequences | Medium |
| 661 | Image Smoother | Easy |
| 662 | Maximum Width of Binary Tree | Medium |
| 664 | Strange Printer | Hard |
| 665 | Non-decreasing Array | Medium |
| 667 | Beautiful Arrangement II | Medium |
| 668 | Kth Smallest Number in Multiplication Table | Hard |
| 669 | Trim a Binary Search Tree | Easy |
| 670 | Maximum Swap | Medium |
| 671 | Second Minimum Node In a Binary Tree | Easy |
| 672 | Bulb Switcher II | Medium |
| 673 | Number of Longest Increasing Subsequence | Medium |
| 674 | Longest Continuous Increasing Subsequence | Easy |
| 675 | Cut Off Trees for Golf Event | Hard |
| 676 | Implement Magic Dictionary | Medium |
| 677 | Map Sum Pairs | Medium |
| 678 | Valid Parenthesis String | Medium |
| 679 | 24 Game | Hard |
| 680 | Valid Palindrome II | Easy |
| 682 | Baseball Game | Easy |
| 684 | Redundant Connection | Medium |