Solutions of problems on leetcode in Sequence [C++]. Intuition behind the solution and optimization technique and time and space complexity analysis.
| # | Title | Difficulty | Solution | Time Complexity | Space Complexity |
|---|---|---|---|---|---|
| 1 | Two Sum | Easy | Solution | TC - O(N) | SC - O(N) |
| 2 | Add Two Numbers | Medium | Solution | TC-O(max(m,n)) | SC-O(max(m,n)) |
| 3 | Longest Substring Without Repeating Characters | Medium | Solution | TC - O(N) | SC - O(min(m,n)) |
| 4 | Median of Two Sorted Arrays | Hard | Solution | TC- O(log(min(m, n))) | SC-O(1) |
| 5 | Longest Palindromic Substring | Medium | Solution | TC-O(N*N) | SC-O(1) |
| 6 | ZigZag Conversion | Medium | Solution | ||
| 7 | Reverse Integer | Easy | Solution | ||
| 8 | String to Integer (atoi) | Medium | Solution | ||
| 9 | Palindrome Number | Easy | Solution | ||
| 10 | Regular Expression Matching | Hard | Solution | ||
| 11 | Container With Most Water | Medium | Solution | ||
| 12 | Integer to Roman | Medium | Solution | ||
| 13 | Roman to Integer | Easy | Solution | ||
| 14 | Longest Common Prefix | Easy | Solution | ||
| 15 | 3Sum | Medium | Solution | ||
| 16 | 3Sum Closest | Medium | Solution | ||
| 17 | Letter Combinations of a Phone Number | Medium | Solution | ||
| 18 | 4Sum | Medium | Solution | ||
| 19 | Remove Nth Node From End of List | Medium | Solution | ||
| 20 | Valid Parentheses | Easy | Solution | ||
| 21 | Merge Two Sorted Lists | Easy | Solution | ||
| 22 | Generate Parentheses | Medium | Solution | ||
| 23 | Merge k Sorted Lists | Hard | Solution | ||
| 24 | Swap Nodes in Pairs | Medium | Solution | ||
| 25 | Reverse Nodes in k-Group | Hard | Solution | ||
| 26 | Remove Duplicates from Sorted Array | Easy | Solution | ||
| 27 | Remove Element | Easy | Solution | ||
| 28 | Find the Index of the First Occurrence in a String | Medium | Solution | ||
| 29 | Divide Two Integers | Medium | Solution | ||
| 30 | Substring with Concatenation of All Words | Hard | Solution | ||
| 31 | Next Permutation | Medium | Solution | ||
| 32 | Longest Valid Parentheses | Hard | Solution | ||
| 33 | Search in Rotated Sorted Array | Medium | Solution | ||
| 34 | Find First and Last Position of Element in Sorted Array | Medium | Solution | ||
| 35 | Search Insert Position | Easy | Solution | ||
| 36 | Valid Sudoku | Medium | Solution | ||
| 37 | Sudoku Solver | Hard | Solution | ||
| 38 | Count and Say | Medium | Solution | ||
| 39 | Combination Sum | Medium | Solution | ||
| 40 | Combination Sum II | Medium | Solution | ||
| 41 | First Missing Positive | Hard | Solution | ||
| 42 | Trapping Rain Water | Hard | Solution | ||
| 43 | Multiply Strings | Medium | Solution | ||
| 44 | Wildcard Matching | Hard | Solution | ||
| 45 | Jump Game II | Medium | Solution | ||
| 46 | Permutations | Medium | Solution | ||
| 47 | Permutations II | Medium | Solution | ||
| 48 | Rotate Image | Medium | Solution | ||
| 49 | Group Anagrams | Medium | Solution | ||
| 50 | Pow(x, n) | Medium | Solution | ||
| 51 | N-Queens | Hard | Solution | ||
| 52 | N-Queens II | Hard | Solution | ||
| 53 | Maximum Subarray | Medium | Solution | ||
| 54 | Spiral Matrix | Medium | Solution | ||
| 55 | Jump Game | Medium | Solution | ||
| 56 | Merge Intervals | Medium | Solution | ||
| 57 | Insert Interval | Medium | Solution | ||
| 58 | Length of Last Word | Easy | Solution | ||
| 59 | Spiral Matrix II | Medium | Solution | ||
| 60 | Permutation Sequence | Hard | Solution | ||
| 61 | Rotate List | Medium | Solution | ||
| 62 | Unique Paths | Medium | Solution | ||
| 63 | Unique Paths II | Medium | Solution | ||
| 64 | Minimum Path Sum | Medium | Solution | ||
| 65 | Valid Number | Hard | Solution | ||
| 66 | Plus One | Easy | Solution | ||
| 67 | Add Binary | Easy | Solution | ||
| 68 | Text Justification | Hard | Solution | ||
| 69 | Sqrt(x) | Easy | Solution | ||
| 70 | Climbing Stairs | Easy | Solution | ||
| 71 | Simplify Path | Medium | Solution | ||
| 72 | Edit Distance | Hard | Solution | ||
| 73 | Set Matrix Zeroes | Medium | Solution | ||
| 74 | Search a 2D Matrix | Medium | Solution | ||
| 75 | Sort Colors | Medium | Solution | ||
| 76 | Minimum Window Substring | Hard | Solution | ||
| 77 | Combinations | Medium | Solution | ||
| 78 | Subsets | Medium | Solution | ||
| 79 | Word Search | Medium | Solution | ||
| 80 | Remove Duplicates from Sorted Array II | Medium | Solution | ||
| 81 | Search in Rotated Sorted Array II | Medium | Solution | ||
| 82 | Remove Duplicates from Sorted List II | Medium | Solution | ||
| 83 | Remove Duplicates from Sorted List | Easy | Solution | ||
| 84 | Largest Rectangle in Histogram | Hard | Solution | ||
| 85 | Maximal Rectangle | Hard | Solution | ||
| 86 | Partition List | Medium | Solution | ||
| 87 | Scramble String | Hard | Solution | ||
| 88 | Merge Sorted Array | Easy | Solution | ||
| 89 | Gray Code | Medium | Solution | ||
| 90 | Subsets II | Medium | Solution | ||
| 91 | Decode Ways | Medium | Solution | ||
| 92 | Reverse Linked List II | Medium | Solution | ||
| 93 | Restore IP Addresses | Medium | Solution | ||
| 94 | Binary Tree Inorder Traversal | Easy | Solution | ||
| 95 | Unique Binary Search Trees II | Medium | Solution | ||
| 96 | Unique Binary Search Trees | Medium | Solution | ||
| 97 | Interleaving String | Medium | Solution | ||
| 98 | Validate Binary Search Tree | Medium | Solution | ||
| 99 | Recover Binary Search Tree | Medium | Solution | ||
| 100 | Same Tree | Easy | Solution | ||
| 144 | Binary Tree Preorder Traversal | Easy | Solution | ||
| 149 | Max points on a Line | Hard | Solution | ||
| 198 | House robber | Medium | Solution | ||
| 443 | String Compression | Medium | Solution | ||
| 567 | Permutation in String | Medium | Solution | ||
| 723 | Candy Crush | Medium | Solution | ||
| 918 | Maximum Sum Circular Subarray | Medium | Solution | ||
| 946 | Validate stack sequence | Medium | Solution | ||
| 1071 | Greatest Common Divisor of Strings | Easy | Solution | ||
| 1137 | N-th Tribonacci Number | Easy | Solution | ||
| 1365 | How Many Numbers Are Smaller Than the Current Number | Easy | Solution | ||
| 1443 | Minimum Time to Collect All Apples in a Tree | Medium | Solution | ||
| 1748 | Sum of Unique Elements | Easy | Solution | ||
| 2068 | Check Whether Two Strings are Almost Equivalent | Easy | Solution | ||
| 2070 | Most Beautiful Item for Each Query | Medium | Solution | ||
| 2073 | Time Needed to Buy Tickets | Easy | Solution | ||
| 2423 | Remove Letter To Equalize Frequency | Easy | Solution | ||
| 2535 | Difference Between Element Sum and Digit Sum of an Array | Easy | Solution | ||
| 2537 | Count the Number of Good Subarrays | Medium | Solution | ||
| 2558 | Take Gifts From the Richest Pile | Easy | Solution | ||
| 2559 | Count Vowel Strings in Ranges | Medium | Solution |