| 51 | N-Queens | ArrayBacktracking | Hard |
| 52 | N-Queens II | Backtracking | Hard |
| 53 | Maximum Subarray | ArrayDivide and ConquerDynamic Programming | Medium |
| 54 | Spiral Matrix | ArrayMatrixSimulation | Medium |
| 55 | Jump Game | ArrayDynamic ProgrammingGreedy | Medium |
| 56 | Merge Intervals | ArraySorting | Medium |
| 57 | Insert Interval | Array | Medium |
| 58 | Length of Last Word | String | Easy |
| 59 | Spiral Matrix II | ArrayMatrixSimulation | Medium |
| 60 | Permutation Sequence | MathRecursion | Hard |
| 61 | Rotate List | Linked ListTwo Pointers | Medium |
| 62 | Unique Paths | MathDynamic ProgrammingCombinatorics | Medium |
| 63 | Unique Paths II | ArrayDynamic ProgrammingMatrix | Medium |
| 64 | Minimum Path Sum | ArrayDynamic ProgrammingMatrix | Medium |
| 65 | Valid Number | String | Hard |
| 66 | Plus One | ArrayMath | Easy |
| 67 | Add Binary | MathStringBit Manipulation+1 | Easy |
| 68 | Text Justification | ArrayStringSimulation | Hard |
| 69 | Sqrt(x) | MathBinary Search | Easy |
| 70 | Climbing Stairs | MathDynamic ProgrammingMemoization | Easy |
| 71 | Simplify Path | StringStack | Medium |
| 72 | Edit Distance | StringDynamic Programming | Medium |
| 73 | Set Matrix Zeroes | ArrayHash TableMatrix | Medium |
| 74 | Search a 2D Matrix | ArrayBinary SearchMatrix | Medium |
| 75 | Sort Colors | ArrayTwo PointersSorting | Medium |
| 76 | Minimum Window Substring | Hash TableStringSliding Window | Hard |
| 77 | Combinations | Backtracking | Medium |
| 78 | Subsets | ArrayBacktrackingBit Manipulation | Medium |
| 79 | Word Search | ArrayStringBacktracking+2 | Medium |
| 80 | Remove Duplicates from Sorted Array II | ArrayTwo Pointers | Medium |
| 81 | Search in Rotated Sorted Array II | ArrayBinary Search | Medium |
| 82 | Remove Duplicates from Sorted List II | Linked ListTwo Pointers | Medium |
| 83 | Remove Duplicates from Sorted List | Linked List | Easy |
| 84 | Largest Rectangle in Histogram | ArrayStackMonotonic Stack | Hard |
| 85 | Maximal Rectangle | ArrayDynamic ProgrammingStack+2 | Hard |
| 86 | Partition List | Linked ListTwo Pointers | Medium |
| 87 | Scramble String | StringDynamic Programming | Hard |
| 88 | Merge Sorted Array | ArrayTwo PointersSorting | Easy |
| 89 | Gray Code | MathBacktrackingBit Manipulation | Medium |
| 90 | Subsets II | ArrayBacktrackingBit Manipulation | Medium |
| 91 | Decode Ways | StringDynamic Programming | Medium |
| 92 | Reverse Linked List II | Linked List | Medium |
| 93 | Restore IP Addresses | StringBacktracking | Medium |
| 94 | Binary Tree Inorder Traversal | StackTreeDepth-First Search+1 | Easy |
| 95 | Unique Binary Search Trees II | Dynamic ProgrammingBacktrackingTree+2 | Medium |
| 96 | Unique Binary Search Trees | MathDynamic ProgrammingTree+2 | Medium |
| 97 | Interleaving String | StringDynamic Programming | Medium |
| 98 | Validate Binary Search Tree | TreeDepth-First SearchBinary Search Tree+1 | Medium |
| 99 | Recover Binary Search Tree | TreeDepth-First SearchBinary Search Tree+1 | Medium |
| 100 | Same Tree | TreeDepth-First SearchBreadth-First Search+1 | Easy |