| 200 | Number of Islands | Medium | depth first search |
| 305 | Number of Islands II | Hard | hash table |
| 323 | Number of Connected Components in an Undirected Graph | Medium | hash table |
| 399 | Evaluate Division | Medium | graph |
| 547 | Friend Circles | Medium | depth first search |
| 684 | Redundant Connection | Medium | tree |
| 685 | Redundant Connection II | Hard | tree |
| 721 | Accounts Merge | Medium | hash table |
| 737 | Sentence Similarity II | Medium | hash table |
| 778 | Swim in Rising Water | Hard | array |
| 803 | Bricks Falling When Hit | Hard | array |
| 839 | Similar String Groups | Hard | string |
| 924 | Minimize Malware Spread | Hard | graph |
| 928 | Minimize Malware Spread II | Hard | graph |
| 947 | Most Stones Removed with Same Row or Column | Medium | array |
| 952 | Largest Component Size by Common Factor | Hard | array |
| 959 | Regions Cut By Slashes | Medium | graph |
| 990 | Satisfiability of Equality Equations | Medium | graph |
| 1061 | Lexicographically Smallest Equivalent String | Medium | string |
| 1101 | The Earliest Moment When Everyone Become Friends | Medium | graph |
| 1135 | Connecting Cities With Minimum Cost | Medium | graph |
| 1168 | Optimize Water Distribution in a Village | Hard | graph |
| 1202 | Smallest String With Swaps | Medium | depth first search |
| 1258 | Synonymous Sentences | Medium | backtracking |
| 1559 | Detect Cycles in 2D Grid | Hard | array |
| 1579 | Remove Max Number of Edges to Keep Graph Fully Traversable | Hard | graph |
| 1584 | Min Cost to Connect All Points | Medium | graph |
| 1627 | Graph Connectivity With Threshold | Hard | graph |
| 1631 | Path With Minimum Effort | Medium | graph |
| 1632 | Rank Transform of a Matrix | Hard | greedy |
| 1697 | Checking Existence of Edge Length Limited Paths | Hard | graph |
| 1722 | Minimize Hamming Distance After Swap Operations | Medium | depth first search |
| 1970 | Last Day Where You Can Still Cross | Hard | array |
| 1998 | GCD Sort of an Array | Hard | array |
| 2076 | Process Restricted Friend Requests | Hard | graph |
| 2092 | Find All People With Secret | Hard | graph |
| 2157 | Groups of Strings | Hard | string |
| 2307 | Check for Contradictions in Equations | Hard | graph |
| 2382 | Maximum Segment Sum After Removals | Hard | array |
| 2421 | Number of Good Paths | Hard | tree |
| 2612 | Minimum Reverse Operations | Hard | breadth first search |
| 2617 | Minimum Number of Visited Cells in a Grid | Hard | breadth first search |
| 2812 | Find the Safest Path in a Grid | Medium | breadth first search |
| 2867 | Count Valid Paths in a Tree | Hard | dynamic programming |
| 3108 | Minimum Cost Walk in Weighted Graph | Hard | graph |
| 3235 | Check if the Rectangle Corner Is Reachable | Hard | graph |
| 3378 | Count Connected Components in LCM Graph | Hard | graph |
| 3493 | Properties Graph | Medium | graph |
| 3600 | Maximize Spanning Tree Stability with Upgrades | Hard | graph |
| 3608 | Minimum Time for K Connected Components | Medium | simulation |
| 3613 | Minimize Maximum Component Cost | Medium | simulation |
| 3710 | Maximum Partition Factor | Hard | graph |
| 3873 | Maximum Points Activated with One Addition | Hard | graph |
| 3887 | Incremental Even-Weighted Cycle Queries | Hard | graph |