SOLUTIONS
LEETCODE.
Hard difficulty analysis and solutions.
| Problem | Difficulty | Complexity | Date |
|---|---|---|---|
| 0315 Count of Smaller Numbers After Self | Hard | T: O(N log N) where N is the length of the array / S: O(N) for the temporary merge buffer and index tracking | Mar 2026 |
| 0321 Create Maximum Number | Hard | T: O(K * (M + N)) where M and N are the lengths of the two arrays / S: O(M + N) | Mar 2026 |
| 0327 Count of Range Sum | Hard | T: O(N log N) where N is the length of the array / S: O(N) for the prefix sum array and the merge buffer | Mar 2026 |
| 0329 Longest Increasing Path in a Matrix | Hard | T: O(M * N) where M and N are the dimensions of the matrix / S: O(M * N) | Mar 2026 |
| 0330 Patching Array | Hard | T: O(M + log N) where M is the length of nums and N is the target / S: O(1) | Mar 2026 |
| 0332 Reconstruct Itinerary | Hard | T: O(E log E) where E is the number of tickets / S: O(E) | Mar 2026 |
| 0335 Self Crossing | Hard | T: O(n) where n is the length of the distance array / S: O(1) | Mar 2026 |
| 0336 Palindrome Pairs | Hard | T: O(N * K^2) / S: O(N * K) | Mar 2026 |
| 0352 Data Stream as Disjoint Intervals | Hard | T: O(log N) per addNum, O(N) per getIntervals, where N is the number of intervals / S: O(N) | Mar 2026 |
| 0354 Russian Doll Envelopes | Hard | T: O(N log N) where N is the number of envelopes / S: O(N) | Mar 2026 |
| 0363 Max Sum of Rectangle No Larger Than K | Hard | T: O(M^2 * N * log N) where M is the number of rows and N is the number of columns / S: O(N) | Mar 2026 |
| 0381 Insert Delete GetRandom O(1) Duplicates Allowed | Hard | T: O(1) amortized per insert, remove, and getRandom / S: O(N), where N is the total number of elements in the collection | Mar 2026 |
| 0391 Perfect Rectangle | Hard | T: O(N) where N is the number of rectangles / S: O(N) | Mar 2026 |
| 0403 Frog Jump | Hard | T: O(N^2) where N is the number of stones / S: O(N^2) | Mar 2026 |
| 0407 Trapping Rain Water II | Hard | T: O(M * N * log(M * N)) where M and N are the dimensions of the matrix / S: O(M * N) | Mar 2026 |
| 0410 Split Array Largest Sum | Hard | T: O(N * log(S)) where N is the length of the array and S is the sum of all elements / S: O(1) | Mar 2026 |
| 0420 Strong Password Checker | Hard | T: O(N) where N is the length of the password / S: O(N) for storing the repeating sequences | Mar 2026 |
| 0432 All O`one Data Structure | Hard | T: O(1) per inc, dec, getMaxKey, and getMinKey operation / S: O(N), where N is the number of distinct keys in the structure | Mar 2026 |
| 0440 K-th Smallest in Lexicographical Order | Hard | T: O(log(n)^2), where n is the upper bound of the range / S: O(1) | Mar 2026 |
| 0446 Arithmetic Slices II - Subsequence | Hard | T: O(N^2), where N is the length of the array / S: O(N^2), for the hash maps stored at each index | Mar 2026 |