| 352 | Data Stream as Disjoint Intervals | Hard |
| 354 | Russian Doll Envelopes | Hard |
| 363 | Max Sum of Rectangle No Larger Than K | Hard |
| 381 | Insert Delete GetRandom O(1) - Duplicates allowed | Hard |
| 391 | Perfect Rectangle | Hard |
| 403 | Frog Jump | Hard |
| 407 | Trapping Rain Water II | Hard |
| 410 | Split Array Largest Sum | Hard |
| 420 | Strong Password Checker | Hard |
| 432 | All O`one Data Structure | Hard |
| 440 | K-th Smallest in Lexicographical Order | Hard |
| 446 | Arithmetic Slices II - Subsequence | Hard |
| 458 | Poor Pigs | Hard |
| 460 | LFU Cache | Hard |
| 466 | Count The Repetitions | Hard |
| 472 | Concatenated Words | Hard |
| 479 | Largest Palindrome Product | Hard |
| 480 | Sliding Window Median | Hard |
| 483 | Smallest Good Base | Hard |
| 488 | Zuma Game | Hard |
| 493 | Reverse Pairs | Hard |
| 502 | IPO | Hard |
| 514 | Freedom Trail | Hard |
| 517 | Super Washing Machines | Hard |
| 546 | Remove Boxes | Hard |
| 552 | Student Attendance Record II | Hard |
| 564 | Find the Closest Palindrome | Hard |
| 587 | Erect the Fence | Hard |
| 591 | Tag Validator | Hard |
| 600 | Non-negative Integers without Consecutive Ones | Hard |