Problems and solutions of Leetcode problems.
Solved using python for practice and reference.
| Leetcode Number | Leetcode Problem Title | Difficulty | Data Structure | Algorithm |
|---|---|---|---|---|
| 1 | Two Sums | Easy | Array | Hashmap |
| 2 | Add Two Numbers | Medium | LinkedList | - |
| 11 | Container with Most Water | Medium | Array | Two pointer |
| 15 | 3Sum | Medium | Array | Two pointer |
| 17 | Letter Combinations of a Phone Number | Medium | Array | Backtracking/Recursion |
| 19 | Remove Nth Node From End of List | Medium | LinkedList | Two pointer |
| 20 | Valid Parentheses | Easy | Stack | Iteration/Hashmap |
| 21 | Merge Two Sorted List | Easy | LinkedList | Sorting |
| 22 | Generate Paranthesis | Medium | Array | Recursion/Backtracking |
| 23 | Merge k Sorted List | Hard | LinkedList | Sorting |
| 24 | Swap nodes in pairs | Medium | LinkedList | Recursion |
| 33 | Search in Rotated SOrted Array | Medium | Array | Binary Search |
| 35 | Search Insert Position | Easy | Array | Binary Search |
| 39 | Combination Sum | Medium | Array | Recursion/Backtracking |
| 40 | Combination Sum | Medium | Array | Recursion/Backtracking |
| 46 | Permutations | Medium | Array | Recursion/Backtracking |
| 47 | Permutations II | Medium | Array | Recursion/Backtracking |
| 49 | Group Anagrams | Medium | Array | Hashmap |
| 51 | N-Queens | Hard | Array | Recursion/Backtracking |
| 64 | Minimum Path Sum | Medium | 2D Array | Dynamic Programming |
| 70 | Climbing Stairs | Easy | Array | Dynamic Programming |
| 72 | Edit Distance | Medium | String | Dynamic Programming |
| 75 | Sort Colors | Medium | Array | Two pointer/Sorting Algorithm |
| 76 | Remove Duplicates in Sorted Array | Easy | Array | Two pointer |
| 77 | Combinations | Medium | Array | Backtracking/Recursion |
| 78 | Subsets | Medium | Array | Recursion/Backtracking |
| 79 | Word Search | Medium | Array | Backtracking |
| 84 | Largest Rectangle in HIstogram | Hard | Array | Stack |
| 100 | Same Tree | Easy | Tree | Recursion |
| 101 | Symmetric Tree | Easy | Tree | Recursion |
| 104 | Maximum Depth of Binary Tree | Easy | tree | BFS |
| 110 | Balanced Binary Tree | Easy | Tree | Recursion |
| 118 | Pascal's Triangle | Easy | Array | Iteration |
| 119 | Pascal's Triangle II | Easy | Array | Iteration/Recursion |
| 121 | Best Time to Buy and Sell Stock | Easy | Array | Sliding Window |
| 123 | Best Time to Buy and Sell Stock III | Hard | Array | Dynamic Programming |
| 125 | Valid Palindrome | Easy | String | Two pointer |
| 128 | Longest Consecutive Sequence | Medium | Array | HashSet |
| 138 | Copy List with Random Pointer | Medium | LinkedList | Two Passes |
| 141 | Linked List Cycle | Easy | LinkedList | Two pointer |
| 143 | Reorder List | Medium | LinkedList | Two pointer |
| 150 | Evaluate Reverse Polish Notation | Medium | Array | Stack |
| 153 | Find Minimum in Rotated Sorted Array | Medium | Array | Binary Search |
| 155 | Min Stack | Medium | Array | Stack |
| 162 | Find Peak Elements | Medium | Array | Binary Search |
| 200 | Number of Islands | Medium | 2D Array | BFS/DFS |
| 203 | Remove Linked List Elements | Easy | LinkedList | Two pointer |
| 206 | Reverse Linked List | Easy | LinkedList | Iteration/Recursive |
| 207 | Course Schedule | Medium | 2D Array | DFS |
| 216 | Combination Sum II | Medium | Array | Backtracking |
| 217 | Contains Duplicate | Easy | Array | - |
| 219 | Contains Duplicate II | Easy | Array | Hashmap |
| 226 | Invert Binary Tree | Easy | Tree | Recursion |
| 237 | Delete Node in a Linked List | Medium | LinkedList | Two pointer |
| 238 | Product of Array Except Self | Medium | Array | - |
| 239 | Sliding Window MAximum | Hard | Array(Deque) | Sliding Window |
| 242 | Valid Anagram | Easy | Array | - |
| 256 | 256_Paint_House | Medium | 2D Array | Dynamic Programming |
| 278 | First Bad Version | Easy | Array | Binary Search |
| 287 | Find the Duplicate Number | Medium | Array/LinkedList | Floyd's Cyclic Detection/Two pointers |
| 344 | Reverse String | Easy | String | Two pointer/Recursion |
| 347 | Top K Frequent Elements | Medium | Array | HashSet |
| 349 | Intersection of Two Arrays | Easy | Array | Binary Search |
| 377 | Combination Sum IV | Medium | Array | Backtracking/Recursion/Dynamic Programming |
| 424 | Longest Repeating Character Replacement | Medium | Array | Binary Search |
| 441 | Arranging coins | Easy | Array | Binary Search |
| 509 | Fibonacci Number | Easy | - | Recursion |
| 542 | Fibonacci Number | Medium | 2D Array | BFS |
| 543 | Diameter of a Binary Tree | Easy | Tree | Recursion/DFS |
| 547 | Number of provinces | Medium | 2D Array | Recursion/DFS |
| 572 | Subtree of Another tree | Easy | Tree | Recursion |
| 643 | Maximum Average Subarray I | Easy | Array | Sliding window |
| 695 | Max Area of Island | Medium | 2DArray | BFS |
| 700 | Search in Binary Search Tree | Easy | Tree | Recursive/ Iteration/BST |
| 704 | Binary Search | Easy | Array | Binary Search |
| 733 | Binary Search | Easy | 2D Array | BFS |
| 739 | Daily Temperatures | Medium | Array | Stack |
| 746 | Min Cost Climbing Stairs | Easy | Array | Dynamic Programming |
| 763 | Partition Labels | Medium | Array | Hashmap |
| 771 | Jewels and Stones | Easy | Array | Counter |
| 784 | Letter Case Permutation | Medium | Array | Backtracking/Iteration |
| 797 | All Paths From Source to Target | Medium | Graph/2D Array | BFS/DFS |
| 853 | Car Fleet | Medium | Array | Stack |
| 875 | Koko Eating Bananas | Medium | Array | Binary Search |
| 876 | Middle of the Linkedlist | Easy | LinkedList | Two pointer |
| 904 | Fruit Into Baskets | Medium | Array | Sliding Window, Two Pointer |
| 922 | Sort Array By Parity II | Easy | Array | Two pointer |
| 944 | Rotting Oranges | Medium | 2D Array | BFS |
| 981 | Time Based Key-Value Store | Medium | Array | Binary Search |
| 983 | Minimum Cost For Tickets | Medium | 2D Array | Dynamic Programming |
| 1004 | Max Consecutive Ones III | Medium | Array | Sliding window, Two pointer |
| 1254 | Number of Closed Islands | Medium | 2DArray | DFS |
| 1365 | How Many Numbers Are Smaller Than the Current Number | Easy | Array | Hashmap |
| 1428 | Minimum Number of Days to Make m Bouquets | Medium | Array | Binary Search |