LeetCode This repository consists of my solutions to the problems on Leetcode. The repo is categorized as follows. LeetCode Algorithms # Title Solution Difficulty Topic 1 Two Sum Java Easy 144 Binary Tree Preorder Traversal Java Medium 26 Remove Duplicates from Sorted Array Java Easy 28 Implement strStr() Java Easy 167 Two Sum II - Input array is sorted Java Easy 27 Remove Element Java Easy 2 Add Two Numbers Java Medium 349 Intersection of Two Arrays Java Easy 9 Palindrome Number Java Easy 35 Search Insert Position Java Easy 100 Same Tree Java Easy 136 Single Number Java Easy 58 Length of Last Word Java, Go Easy 501 Find Mode in Binary Search Tree Java Easy 66 Plus One Java Easy 146 LRU Cache Java Medium 69 Sqrt(x) Java Easy 202 Happy Number Java / Python Easy 83 Remove Duplicates from Sorted List Java Easy 88 Merge Sorted Array Java Easy 500 Keyboard Row Java Easy 232 Implement Queue using Stacks Java Easy 238 Product of Array Except Self Java Medium 387 First Unique Character in a String Java Easy 206 Reverse Linked List Java Easy 141 Linked List Cycle Java Easy 278 First Bad Version Java Easy 102 Binary Tree Level Order Traversal Java Medium 189 Rotate Array Java Easy 20 Valid Parentheses Java Easy 21 Merge Two Sorted Lists Java Easy 121 Best Time to Buy and Sell Stock Java Easy 94 Binary Tree Inorder Traversal Java Medium 237 Delete Node in a Linked List Java Easy 42 Trapping Rain Water Java Hard 98 Validate Binary Search Tree Java Medium 145 Binary Tree Postorder Traversal Java Hard 155 Min Stack Java Easy 173 Binary Search Tree Iterator Java Medium 41 First Missing Positive Java Hard 268 Missing Number Java Easy 53 Maximum Subarray Java Easy 138 Copy List with Random Pointer Java Medium 412 Fizz Buzz Java Easy 937 Reorder Data in Log Files Java Easy 200 Number of Islands Java Medium 1086 High Five Java Easy 977 Squares of a Sorted Array Java Easy 953 Verifying an Alien Dictionary Java Easy 23 Merge k Sorted Lists Java Hard 706 Design HashMap Java Easy 819 Most Common Word Java Easy 283 Move Zeroes Java Easy 49 Group Anagrams Java Medium ? Counting Elements Java ? 876 Middle of the Linked List Java Easy 369 Plus One Linked List Java Medium 844 Backspace String Compare Java Easy 104 Maximum Depth of Binary Tree Java Easy 543 Diameter of Binary Tree Java Easy 415 Add Strings Java Easy 443 String Compression Java Easy 1046 Last Stone Weight Java Easy ? Perform String Shifts Java ? 525 Contiguous Array Java Medium 125 Valid Palindrome Java Easy 485 Max Consecutive Ones Java Easy 1295 Find Numbers with Even Number of Digits Java Easy 678 Valid Parenthesis String Java Medium 64 Minimum Path Sum Java Medium 33 Search in Rotated Sorted Array Java Medium 1008 Construct Binary Search Tree from Preorder Traversal Java Medium ? Leftmost Column with at Least a One Java ? 560 Subarray Sum Equals K Java Medium 201 Bitwise AND of Numbers Range Java Medium 55 Jump Game Java Medium 221 Maximal Square Java Medium ? First Unique Number Java ? 124 Binary Tree Maximum Path Sum Java Hard ? Check String Is Valid Sequence from Root to Leaves Path in a Binary Tree Java ? 448 Find All Numbers Disappeared in an Array Java Easy 1089 Duplicate Zeros Java Easy 203 Remove Linked List Elements Java Easy 896 Monotonic Array Java Easy 19 Remove Nth Node From End of List Java Medium 101 Symmetric Tree Java Easy 234 Palindrome Linked List Java Easy 532 K-diff Pairs in an Array Java Medium 701 Insert into a Binary Search Tree Java Medium 15 3Sum Java Medium 704 Binary Search Java Easy 449 Serialize and Deserialize BST Java Medium 1119 Remove Vowels from a String Java Easy 1328 Break a Palindrome Java Medium 454 4Sum II Java Medium 334 Increasing Triplet Subsequence Java Medium 46 Permutations Java Medium 1480 Running Sum of 1d Array Java Easy 1331 Rank Transform of an Array Java Easy 1550 Three Consecutive Odds Java Easy 832 Flipping an Image Java Easy 1640 Check Array Formation Through Concatenation Java Easy 1662 Check If Two String Arrays are Equivalent Java Easy 339 Nested List Weight Sum Java Easy 112 Path Sum Java Easy 169 Majority Element Java Easy 1822 Sign of the Product of an Array Java Easy 24 Swap Nodes in Pairs Java Medium 7 Reverse Integer Java Medium 700 Search in a Binary Search Tree Java Easy 34 Find First and Last Position of Element in Sorted Array Java Medium Binary Search 744 Find Smallest Letter Greater Than Target Java Easy Binary Search 1768 Merge Strings Alternately Java Easy Arrays 1832 Check if the Sentence Is Pangram Java Easy String 67 Add Binary Java Medium String 540 Single Element in a Sorted Array Java, Go Medium Array