LeetCode LeetCode Problems with Solutions # Problem Solution Difficulty 1 Two Sum PHP, JS Easy 3 Longest Substring Without Repeating Characters PHP Medium 5 Longest Palindromic Substring PHP Medium 7 Reverse Integer PHP Medium 15 3Sum PHP Medium 20 Valid Parentheses PHP, JS Easy 23 Merge K Sorted Lists PHP Hard 24 Swap Nodes in Pairs PHP Medium 28 Find the Index of the First Occurence in a String PHP Medium 33 Search in Rotated Sorted Array PHP Medium 35 Search Insert Position PHP Easy 49 Group Anagrams PHP Medium 53 Maximum Subarray PHP Medium 55 Jump Game PHP Medium 58 Length of Last Word PHP, JS Easy 61 Rotate List PHP Medium 83 Remove Duplicates from Sorted List PHP, JS Easy 88 Merge Sorted Array PHP Easy 94 Binary Tree Inorder Traversal PHP Easy 104 Maximum Depth of Binary Tree PHP Easy 105 Construct Binary Tree from Preorder and Inorder Traversal PHP Medium 111 Minimum Depth of Binary Tree PHP Easy 121 Best Time To Buy and Sell Stock PHP, JS Easy 134 Gas Station PHP Medium 142 Linked List Cycle II PHP Medium 144 Binary Tree Preorder Traversal PHP Easy 145 Binary Tree Postorder Traversal PHP Easy 155 Min Stack PHP Medium 167 Two Sum II - Input Array is Sorted PHP Medium 189 Rotate Array PHP Medium 198 House Robber PHP Medium 200 Number of Islands PHP Medium 203 Remove Linked List Elements PHP Easy 207 Course Schedule PHP Medium 213 House Robber II PHP Medium 230 Kth Smallest Element In a BST PHP Medium 238 Product of Array Except Self PHP Medium 303 Range Sum Query - Immutable PHP Easy 347 Top K Frequent Elements PHP Medium 417 Pacific Atlantic Water Flow PHP Medium 438 Find All Anagrams in a String PHP Medium 540 Single Element In a Sorted Array PHP Medium 547 Number of Provinces PHP Medium 560 Subarray Sum Equals K PHP Medium 622 Design Circular Queue PHP Medium 647 Palindromic Substrings PHP Medium 678 Valid Parenthesis String PHP Medium 704 Binary Search PHP Easy 707 Design Linked List PHP Medium 746 Min Cost Climbing Stairs PHP Easy 846 Hand of Straights PHP Medium 875 Koko Eating Bananas PHP Medium 904 Fruit Into Baskets PHP Medium 977 Squares of a Sorted Array PHP Easy 1137 N-th Tribonacci Number PHP Easy 1202 Smallest String With Swaps PHP Medium 1876 Substrings of Size Three with Distinct Characters PHP Easy 1909 Remove One Element to Make the Array Strictly Increasing PHP Easy 1971 Find If Path Exists in Graph PHP Easy 2500 Delete Greatest Element in Each Row PHP Easy