LeetCode Solutions Hard Sl No. Problem Code 1 Minimum Number of Increments on Subarrays to Form a Target Array Code 2 Permutation Sequence Code 3 Word Search II Code Medium Sl No. Problem Code 1 Maximum Subarray Code 2 Jump Game Code 3 Path Sum II Code 4 Sum Root to Leaf Numbers Code 5 House Robber Code 6 House Robber II Code 7 House Robber III Code 8 Append k Integers with Minimum Sum Code 9 Next Permutation Code 10 Sort Colors Code 11 Rotate Image Code 12 Set Matrix Zeroes Code 13 Max Area of Island Code 14 Implement Trie Prefix Tree Code 15 Merge Intervals Code 16 Populating Next Right Pointers in Each Node Code 17 Palindrome Linked List Code 18 Remove Nth Node From End of Linked List Code 19 Combination Sum Code 20 Combination Sum II Code 21 Subsets II Code 22 Permutation Sequence Code 23 Palindrome Partitioning Code 24 Maximum Product Subarray Code 25 Group Anagrams Code 26 Unique Paths Code 27 Add Two Numbers Code 28 Longest Substring Without Repeating Characters Code 29 3Sum Code 30 Find Last and First Position of Element in Sorted Array Code 31 Two Sum II - Input Array is Sorted Code 32 Container with Most Water Code Easy Sl No. Problem Code 1 Roman to Integer Code 2 Two Sum Code 3 Palindrome Number Code 4 Climbing Stairs Code 5 Path Sum Code 6 Pascals Triangle Code 7 Pascals Triangle II Code 8 Best Time to Buy and Sell Stock Code 9 Counting Bits Code 10 Is Subsequence Code 11 Min Cost Climbing Stairs Code 12 Binary Search Code 13 Fibonacci Number Code 14 N-th Tribonacci Number Code 15 Get Maximum in Generated Array Code 16 Cells in a Range on an Excel Sheet Code 17 Valid Parenthesis Code 18 First Bad Version Code 19 Plus One Code 20 Sqrtx Code 21 Remove Duplicates from Sorted List Code 22 Reverse Linked List Code 23 Middle of the Linked List Code 24 Merge Sorted Array Code 25 Linked List Cycle Code 26 Longest Common Prefix Code 27 Binary Tree Inorder Traversal Code 28 Remove Duplicates from Sorted Array Code 29 Valid Palindrome Code 30 Merge Two Sorted Lists Code 31 Search Insert Position Code 32 Length of Last Word Code 33 Single Number Code 34 Majority Element Code 35 Symmetric Tree Code 36 Add Binary Code 37 Reverse Vowels of a String Code 38 Happy Number Code 39 Intersection of Two Linked Lists Code