| 86 | Partition List | Medium | 1519 | linked-listtwo-pointers |
| 90 | Subsets II | Medium | 1517 | arraybacktrackingbit-manipulation |
| 91 | Decode Ways | Medium | 1635 | stringdynamic-programming |
| 92 | Reverse Linked List II | Medium | 1559 | linked-list |
| 93 | Restore IP Addresses | Medium | 1627 | backtrackingstring |
| 95 | Unique Binary Search Trees II | Medium | — | dynamic-programmingbacktrackingtree+2 |
| 96 | Unique Binary Search Trees | Medium | — | mathdynamic-programmingtree+2 |
| 97 | Interleaving String | Medium | 1785 | stringdynamic-programming |
| 98 | Validate Binary Search Tree | Medium | 1490 | treedepth-first-searchbinary-search-tree+1 |
| 99 | Recover Binary Search Tree | Medium | — | treedepth-first-searchbinary-search-tree+1 |
| 102 | Binary Tree Level Order Traversal | Medium | 1308 | treebreadth-first-searchbinary-tree |
| 103 | Binary Tree Zigzag Level Order Traversal | Medium | 1576 | treebreadth-first-searchbinary-tree |
| 105 | Construct Binary Tree from Preorder and Inorder Traversal | Medium | 1643 | arrayhash-tabledivide-and-conquer+2 |
| 106 | Construct Binary Tree from Inorder and Postorder Traversal | Medium | 1660 | arrayhash-tabledivide-and-conquer+2 |
| 107 | Binary Tree Level Order Traversal II | Medium | 1436 | treebreadth-first-searchbinary-tree |
| 109 | Convert Sorted List to Binary Search Tree | Medium | — | linked-listdivide-and-conquertree+2 |
| 114 | Flatten Binary Tree to Linked List | Medium | 1519 | linked-liststacktree+2 |
| 116 | Populating Next Right Pointers in Each Node | Medium | — | linked-listtreedepth-first-search+2 |
| 117 | Populating Next Right Pointers in Each Node II | Medium | 1628 | linked-listtreedepth-first-search+2 |
| 120 | Triangle | Medium | 1533 | arraydynamic-programming |
| 122 | Best Time to Buy and Sell Stock II | Medium | 1486 | arraydynamic-programminggreedy |
| 128 | Longest Consecutive Sequence | Medium | 1680 | arrayhash-tableunion-find |
| 129 | Sum Root to Leaf Numbers | Medium | 1399 | treedepth-first-searchbinary-tree |
| 130 | Surrounded Regions | Medium | 1706 | arraydepth-first-searchbreadth-first-search+2 |
| 131 | Palindrome Partitioning | Medium | 1615 | stringdynamic-programmingbacktracking |
| 133 | Clone Graph | Medium | 1521 | hash-tabledepth-first-searchbreadth-first-search+1 |
| 134 | Gas Station | Medium | 1767 | arraygreedy |
| 137 | Single Number II | Medium | 1710 | arraybit-manipulation |
| 138 | Copy List with Random Pointer | Medium | 1618 | hash-tablelinked-list |
| 139 | Word Break | Medium | 1673 | arrayhash-tablestring+3 |
| 142 | Linked List Cycle II | Medium | 1484 | linked-listtwo-pointershash-table |
| 143 | Reorder List | Medium | 1532 | linked-listtwo-pointersstack+1 |
| 146 | LRU Cache | Medium | 1793 | hash-tablelinked-listdesign+1 |
| 147 | Insertion Sort List | Medium | 1620 | linked-listsorting |
| 148 | Sort List | Medium | 1636 | linked-listtwo-pointersdivide-and-conquer+2 |
| 150 | Evaluate Reverse Polish Notation | Medium | 1492 | arraymathstack |
| 151 | Reverse Words in a String | Medium | 1384 | two-pointersstring |
| 152 | Maximum Product Subarray | Medium | 1555 | arraydynamic-programming |
| 153 | Find Minimum in Rotated Sorted Array | Medium | 1485 | arraybinary-search |
| 155 | Min Stack | Medium | 1419 | stackdesign |
| 162 | Find Peak Element | Medium | 1536 | arraybinary-search |
| 167 | Two Sum II - Input Array Is Sorted | Medium | 1389 | arraytwo-pointersbinary-search |
| 172 | Factorial Trailing Zeroes | Medium | 1399 | math |
| 173 | Binary Search Tree Iterator | Medium | 1569 | stacktreedesign+3 |
| 179 | Largest Number | Medium | — | arraystringgreedy+1 |
| 187 | Repeated DNA Sequences | Medium | — | hash-tablestringbit-manipulation+3 |
| 189 | Rotate Array | Medium | 1433 | arraymathtwo-pointers |
| 198 | House Robber | Medium | 1514 | arraydynamic-programming |
| 199 | Binary Tree Right Side View | Medium | 1454 | treedepth-first-searchbreadth-first-search+1 |
| 200 | Number of Islands | Medium | 1580 | arraydepth-first-searchbreadth-first-search+2 |