| 539 | Minimum Time Difference | ArrayMathString+1 | Medium |
| 540 | Single Element in a Sorted Array | ArrayBinary Search | Medium |
| 542 | 01 Matrix | ArrayDynamic ProgrammingBreadth-First Search+1 | Medium |
| 547 | Number of Provinces | Depth-First SearchBreadth-First SearchUnion Find+1 | Medium |
| 550 | Game Play Analysis IV | Database | Medium |
| 553 | Optimal Division | ArrayMathDynamic Programming | Medium |
| 554 | Brick Wall | ArrayHash Table | Medium |
| 556 | Next Greater Element III | MathTwo PointersString | Medium |
| 558 | Logical OR of Two Binary Grids Represented as Quad-Trees | Divide and ConquerTree | Medium |
| 560 | Subarray Sum Equals K | ArrayHash TablePrefix Sum | Medium |
| 565 | Array Nesting | ArrayDepth-First Search | Medium |
| 567 | Permutation in String | Hash TableTwo PointersString+1 | Medium |
| 570 | Managers with at Least 5 Direct Reports | Database | Medium |
| 576 | Out of Boundary Paths | Dynamic Programming | Medium |
| 581 | Shortest Unsorted Continuous Subarray | ArrayTwo PointersStack+3 | Medium |
| 583 | Delete Operation for Two Strings | StringDynamic Programming | Medium |
| 585 | Investments in 2016 | Database | Medium |
| 592 | Fraction Addition and Subtraction | MathStringSimulation | Medium |
| 593 | Valid Square | MathGeometry | Medium |
| 602 | Friend Requests II: Who Has the Most Friends | Database | Medium |
| 606 | Construct String from Binary Tree | StringTreeDepth-First Search+1 | Medium |
| 608 | Tree Node | Database | Medium |
| 609 | Find Duplicate File in System | ArrayHash TableString | Medium |
| 611 | Valid Triangle Number | ArrayTwo PointersBinary Search+2 | Medium |
| 621 | Task Scheduler | ArrayHash TableGreedy+3 | Medium |
| 622 | Design Circular Queue | ArrayLinked ListDesign+1 | Medium |
| 623 | Add One Row to Tree | TreeDepth-First SearchBreadth-First Search+1 | Medium |
| 624 | Maximum Distance in Arrays | ArrayGreedy | Medium |
| 626 | Exchange Seats | Database | Medium |
| 633 | Sum of Square Numbers | MathTwo PointersBinary Search | Medium |
| 636 | Exclusive Time of Functions | ArrayStack | Medium |
| 638 | Shopping Offers | ArrayDynamic ProgrammingBacktracking+3 | Medium |
| 640 | Solve the Equation | MathStringSimulation | Medium |
| 641 | Design Circular Deque | ArrayLinked ListDesign+1 | Medium |
| 646 | Maximum Length of Pair Chain | ArrayDynamic ProgrammingGreedy+1 | Medium |
| 647 | Palindromic Substrings | Two PointersStringDynamic Programming | Medium |
| 648 | Replace Words | ArrayHash TableString+1 | Medium |
| 649 | Dota2 Senate | StringGreedyQueue | Medium |
| 650 | 2 Keys Keyboard | MathDynamic Programming | Medium |
| 652 | Find Duplicate Subtrees | Hash TableTreeDepth-First Search+1 | Medium |
| 654 | Maximum Binary Tree | ArrayDivide and ConquerStack+3 | Medium |
| 655 | Print Binary Tree | TreeDepth-First SearchBreadth-First Search+1 | Medium |
| 658 | Find K Closest Elements | ArrayTwo PointersBinary Search+3 | Medium |
| 659 | Split Array into Consecutive Subsequences | ArrayHash TableGreedy+1 | Medium |
| 662 | Maximum Width of Binary Tree | TreeDepth-First SearchBreadth-First Search+1 | Medium |
| 665 | Non-decreasing Array | Array | Medium |
| 667 | Beautiful Arrangement II | ArrayMath | Medium |
| 669 | Trim a Binary Search Tree | TreeDepth-First SearchBinary Search Tree+1 | Medium |
| 670 | Maximum Swap | MathGreedy | Medium |
| 672 | Bulb Switcher II | MathBit ManipulationDepth-First Search+1 | Medium |