SOLUTIONS
LEETCODE.
Analysis and solutions for algorithmic problems.
| Problem | Difficulty | Complexity | Date |
|---|---|---|---|
| 0001 Two Sum | Easy | T: O(n) / S: O(n) | Jan 2026 |
| 0003 Longest Substring Without Repeating Characters | Medium | T: O(n) / S: O(1) | Mar 2026 |
| 0005 Longest Palindromic Substring | Medium | T: O(n^2) / S: O(n) | Mar 2026 |
| 0006 Zigzag Conversion | Medium | T: O(n) / S: O(1) | Jan 2026 |
| 0007 Reverse Integer | Medium | T: O(log x) / S: O(1) | Mar 2026 |
| 0008 String to Integer (atoi) | Medium | T: O(n) / S: O(1) | Jan 2026 |
| 0009 Palindrome Number | Easy | T: O(log n) / S: O(1) | Mar 2026 |
| 0010 Regular Expression Matching | Hard | T: O(M * N) / S: O(M * N) | Mar 2026 |
| 0032 Longest Valid Parentheses | Hard | T: O(N) / S: O(N) | Mar 2026 |
| 0037 Sudoku Solver | Hard | T: O(9^M) where M is the number of empty cells / S: O(M) | Mar 2026 |
| 0041 First Missing Positive | Hard | T: O(N) / S: O(1) | Mar 2026 |
| 0042 Trapping Rain Water | Hard | T: O(N) / S: O(1) | Mar 2026 |
| 0044 Wildcard Matching | Hard | T: O(M * N) / S: O(1) | Mar 2026 |
| 0051 N-Queens | Hard | T: O(N!) / S: O(N) | Mar 2026 |
| 0052 N-Queens II | Hard | T: O(N!) / S: O(1) | Mar 2026 |
| 0056 Merge Intervals | Medium | T: O(n log n) / S: O(n) | Mar 2026 |
| 0060 Permutation Sequence | Hard | T: O(N^2) / S: O(N) | Mar 2026 |
| 0065 Valid Number | Hard | T: O(N) / S: O(1) | Mar 2026 |
| 0066 Plus One | Easy | T: O(n) / S: O(1) | Mar 2026 |
| 0068 Text Justification | Hard | T: O(N) / S: O(N) | Mar 2026 |