| 552 | Student Attendance Record II | Dynamic Programming | Hard |
| 553 | Optimal Division | ArrayMathDynamic Programming | Medium |
| 554 | Brick Wall | ArrayHash Table | Medium |
| 556 | Next Greater Element III | MathTwo PointersString | Medium |
| 557 | Reverse Words in a String III | Two PointersString | Easy |
| 558 | Logical OR of Two Binary Grids Represented as Quad-Trees | Divide and ConquerTree | Medium |
| 559 | Maximum Depth of N-ary Tree | TreeDepth-First SearchBreadth-First Search | Easy |
| 560 | Subarray Sum Equals K | ArrayHash TablePrefix Sum | Medium |
| 561 | Array Partition | ArrayGreedySorting+1 | Easy |
| 563 | Binary Tree Tilt | TreeDepth-First SearchBinary Tree | Easy |
| 564 | Find the Closest Palindrome | MathString | Hard |
| 565 | Array Nesting | ArrayDepth-First Search | Medium |
| 566 | Reshape the Matrix | ArrayMatrixSimulation | Easy |
| 567 | Permutation in String | Hash TableTwo PointersString+1 | Medium |
| 570 | Managers with at Least 5 Direct Reports | Database | Medium |
| 572 | Subtree of Another Tree | TreeDepth-First SearchString Matching+2 | Easy |
| 575 | Distribute Candies | ArrayHash Table | Easy |
| 576 | Out of Boundary Paths | Dynamic Programming | Medium |
| 577 | Employee Bonus | Database | Easy |
| 581 | Shortest Unsorted Continuous Subarray | ArrayTwo PointersStack+3 | Medium |
| 583 | Delete Operation for Two Strings | StringDynamic Programming | Medium |
| 584 | Find Customer Referee | Database | Easy |
| 585 | Investments in 2016 | Database | Medium |
| 586 | Customer Placing the Largest Number of Orders | Database | Easy |
| 587 | Erect the Fence | ArrayMathGeometry | Hard |
| 589 | N-ary Tree Preorder Traversal | StackTreeDepth-First Search | Easy |
| 590 | N-ary Tree Postorder Traversal | StackTreeDepth-First Search | Easy |
| 591 | Tag Validator | StringStack | Hard |
| 592 | Fraction Addition and Subtraction | MathStringSimulation | Medium |
| 593 | Valid Square | MathGeometry | Medium |
| 594 | Longest Harmonious Subsequence | ArrayHash TableSliding Window+2 | Easy |
| 595 | Big Countries | Database | Easy |
| 596 | Classes With at Least 5 Students | Database | Easy |
| 598 | Range Addition II | ArrayMath | Easy |
| 599 | Minimum Index Sum of Two Lists | ArrayHash TableString | Easy |
| 600 | Non-negative Integers without Consecutive Ones | Dynamic Programming | Hard |
| 601 | Human Traffic of Stadium | Database | Hard |
| 602 | Friend Requests II: Who Has the Most Friends | Database | Medium |
| 605 | Can Place Flowers | ArrayGreedy | Easy |
| 606 | Construct String from Binary Tree | StringTreeDepth-First Search+1 | Medium |
| 607 | Sales Person | Database | Easy |
| 608 | Tree Node | Database | Medium |
| 609 | Find Duplicate File in System | ArrayHash TableString | Medium |
| 610 | Triangle Judgement | Database | Easy |
| 611 | Valid Triangle Number | ArrayTwo PointersBinary Search+2 | Medium |
| 617 | Merge Two Binary Trees | TreeDepth-First SearchBreadth-First Search+1 | Easy |
| 619 | Biggest Single Number | Database | Easy |
| 620 | Not Boring Movies | Database | Easy |
| 621 | Task Scheduler | ArrayHash TableGreedy+3 | Medium |
| 622 | Design Circular Queue | ArrayLinked ListDesign+1 | Medium |