| 344 | Reverse String | Easy | — | two-pointersstring |
| 345 | Reverse Vowels of a String | Easy | 1210 | stringtwo-pointers |
| 347 | Top K Frequent Elements | Medium | 1540 | arrayhash-tabledivide-and-conquer+5 |
| 352 | Data Stream as Disjoint Intervals | Hard | 1700 | binary-searchdesignordered-set |
| 355 | Design Twitter | Medium | 1479 | hash-tablelinked-listdesign+1 |
| 367 | Valid Perfect Square | Easy | — | mathbinary-search |
| 370 | Range Addition | Medium | 1607 | arrayprefix-sum |
| 371 | Sum of Two Integers | Medium | 1564 | mathbit-manipulation |
| 373 | Find K Pairs with Smallest Sums | Medium | 1710 | arrayheap-priority-queue |
| 374 | Guess Number Higher or Lower | Easy | 1100 | binary-searchinteractive |
| 375 | Guess Number Higher or Lower II | Medium | — | mathdynamic-programminggame-theory |
| 377 | Combination Sum IV | Medium | 1609 | arraydynamic-programming |
| 378 | Kth Smallest Element in a Sorted Matrix | Medium | 1457 | arraybinary-searchsorting+2 |
| 380 | Insert Delete GetRandom O(1) | Medium | 1571 | arrayhash-tablemath+2 |
| 381 | Insert Delete GetRandom O(1) - Duplicates allowed | Hard | — | arrayhash-tablemath+2 |
| 383 | Ransom Note | Easy | 1139 | hash-tablestringcounting |
| 384 | Shuffle an Array | Medium | — | arraymathdesign+1 |
| 386 | Lexicographical Numbers | Medium | 1433 | depth-first-searchtrie |
| 387 | First Unique Character in a String | Easy | — | hash-tablestringqueue+1 |
| 389 | Find the Difference | Easy | 1215 | hash-tablestringbit-manipulation+1 |
| 392 | Is Subsequence | Easy | 1282 | two-pointersstringdynamic-programming |
| 394 | Decode String | Medium | 1540 | stackstringrecursion |
| 399 | Evaluate Division | Medium | 1747 | arraystringdepth-first-search+4 |
| 400 | Nth Digit | Medium | 1648 | mathbinary-search |
| 402 | Remove K Digits | Medium | 1792 | stringgreedystack+1 |
| 406 | Queue Reconstruction by Height | Medium | 1506 | arraygreedysorting |
| 407 | Trapping Rain Water II | Hard | 2200 | arraybreadth-first-searchheap-priority-queue+1 |
| 408 | Valid Word Abbreviation | Easy | 1239 | two-pointersstring |
| 409 | Longest Palindrome | Easy | 1132 | hash-tablestringgreedy |
| 410 | Split Array Largest Sum | Hard | 1856 | arraybinary-searchdynamic-programming+2 |
| 412 | Fizz Buzz | Easy | 1134 | mathstringsimulation |
| 415 | Add Strings | Easy | 1307 | stringmathsimulation |
| 416 | Partition Equal Subset Sum | Medium | 1624 | arraydynamic-programming |
| 417 | Pacific Atlantic Water Flow | Medium | 1707 | arraydepth-first-searchbreadth-first-search+1 |
| 421 | Maximum XOR of Two Numbers in an Array | Medium | 1712 | arrayhash-tablebit-manipulation+1 |
| 424 | Longest Repeating Character Replacement | Medium | 1680 | hash-tablestringsliding-window |
| 427 | Construct Quad Tree | Medium | 1464 | arraydivide-and-conquertree+1 |
| 433 | Minimum Genetic Mutation | Medium | 1671 | hash-tablestringbreadth-first-search |
| 435 | Non-overlapping Intervals | Medium | 1567 | arraydynamic-programminggreedy+1 |
| 436 | Find Right Interval | Medium | 1416 | arraybinary-searchsorting |
| 437 | Path Sum III | Medium | — | treedepth-first-searchbinary-tree |
| 438 | Find All Anagrams in a String | Medium | 1483 | hash-tablestringsliding-window |
| 440 | K-th Smallest in Lexicographic Order | Hard | 1982 | trie |
| 441 | Arranging Coins | Easy | 1295 | mathbinary-search |
| 443 | String Compression | Medium | 1449 | stringtwo-pointers |
| 445 | Add Two Numbers II | Medium | — | linked-listmathstack |
| 448 | Find All Numbers Disappeared in an Array | Easy | — | arrayhash-table |
| 449 | Serialize and Deserialize BST | Medium | — | stringtreedepth-first-search+4 |
| 450 | Delete Node in a BST | Medium | 1590 | treebinary-search-treebinary-tree |
| 452 | Minimum Number of Arrows to Burst Balloons | Medium | 1703 | arraygreedysorting |