| 301. Remove Invalid Parentheses | Solution | Solve | Hard | | |
| 302. Smallest Rectangle Enclosing Black Pixels | Solution | Solve | Hard | | |
| 305. Number of Islands II | Solution | Solve | Hard | | |
| 312. Burst Balloons | Solution | Solve | Hard | | |
| 315. Count of Smaller Numbers After Self | Solution | Solve | Hard | | |
| 317. Shortest Distance from All Buildings | Solution | Solve | Hard | | |
| 321. Create Maximum Number | Solution | Solve | Hard | | |
| 327. Count of Range Sum | Solution | Solve | Hard | | |
| 329. Longest Increasing Path in a Matrix | Solution | Solve | Hard | | |
| 330. Patching Array | Solution | Solve | Hard | | |
| 332. Reconstruct Itinerary | Solution | Solve | Hard | | |
| 335. Self Crossing | Solution | Solve | Hard | | |
| 336. Palindrome Pairs | Solution | Solve | Hard | | |
| 352. Data Stream as Disjoint Intervals | Solution | Solve | Hard | | |
| 354. Russian Doll Envelopes | Solution | Solve | Hard | | |
| 358. Rearrange String k Distance Apart | Solution | Solve | Hard | | |
| 363. Max Sum of Rectangle No Larger Than K | Solution | Solve | Hard | | |
| 381. Insert Delete GetRandom O(1) - Duplicates allowed | Solution | Solve | Hard | | |
| 391. Perfect Rectangle | Solution | Solve | Hard | | |
| 403. Frog Jump | Solution | Solve | Hard | | |
| 407. Trapping Rain Water II | Solution | Solve | Hard | | |
| 410. Split Array Largest Sum | Solution | Solve | Hard | | |
| 411. Minimum Unique Word Abbreviation | Solution | Solve | Hard | | |
| 420. Strong Password Checker | Solution | Solve | Hard | | |
| 425. Word Squares | Solution | Solve | Hard | | |
| 428. Serialize and Deserialize N-ary Tree | Solution | Solve | Hard | | |
| 431. Encode N-ary Tree to Binary Tree | Solution | Solve | Hard | - | |
| 432. All O`one Data Structure | Solution | Solve | Hard | | |
| 440. K-th Smallest in Lexicographical Order | Solution | Solve | Hard | | |
| 446. Arithmetic Slices II - Subsequence | Solution | Solve | Hard | | |
| 458. Poor Pigs | Solution | Solve | Hard | | |
| 460. LFU Cache | Solution | Solve | Hard | | |
| 465. Optimal Account Balancing | Solution | Solve | Hard | | |
| 466. Count The Repetitions | Solution | Solve | Hard | | |
| 471. Encode String with Shortest Length | Solution | Solve | Hard | | |
| 472. Concatenated Words | Solution | Solve | Hard | | |
| 479. Largest Palindrome Product | Solution | Solve | Hard | | |
| 480. Sliding Window Median | Solution | Solve | Hard | | |
| 483. Smallest Good Base | Solution | Solve | Hard | | |
| 488. Zuma Game | Solution | Solve | Hard | | |
| 489. Robot Room Cleaner | Solution | Solve | Hard | | |
| 493. Reverse Pairs | Solution | Solve | Hard | | |
| 499. The Maze III | Solution | Solve | Hard | | |
| 502. IPO | Solution | Solve | Hard | | |
| 514. Freedom Trail | Solution | Solve | Hard | | |
| 517. Super Washing Machines | Solution | Solve | Hard | | |
| 527. Word Abbreviation | Solution | Solve | Hard | | |
| 546. Remove Boxes | Solution | Solve | Hard | | |
| 548. Split Array with Equal Sum | Solution | Solve | Hard | | |
| 552. Student Attendance Record II | Solution | Solve | Hard | | |
