LeetCode # Title Difficulty go java 1 Two Sum Easy go Java 2 Add Two Numbers Medium go Java 3 Longest Substring Without Repeating Characters Medium go Java 4 Median of Two Sorted Arrays Hard go Java 5 Longest Palindromic Substring Medium go Java 6 ZigZag Conversion Medium go Java 7 Reverse Integer Easy go Java 8 String to Integer (atoi) Medium go Java 9 Palindrome Number Easy Java 10 Regular Expression Matching Hard Java 11 Container With Most Water Medium Java 12 Integer to Roman Medium Java 13 Roman to Integer Easy Java 14 Longest Common Prefix Easy Java 15 3Sum Medium Java 16 3Sum Closest Medium Java 17 Letter Combinations of a Phone Number Medium Java 18 4Sum Medium Java 19 Remove Nth Node From End of List Medium Java 20 Valid Parentheses Easy Java 21 Merge Two Sorted Lists Easy Java 22 Generate Parentheses Medium Java 23 Merge k Sorted Lists Hard Java 24 Swap Nodes in Pairs Medium Java 25 Reverse Nodes in k-Group Hard Java 26 Remove Duplicates from Sorted Array Easy Java 27 Remove Element Easy Java 28 Implement strStr() Easy Java 29 Divide Two Integers Medium Java 30 Substring with Concatenation of All Words Hard Java 31 Next Permutation Medium Java 32 Longest Valid Parentheses Hard Java 33 Search in Rotated Sorted Array Medium Java 34 Search for a Range Medium Java 35 Search Insert Position Easy Java 36 Valid Sudoku Medium Java 37 Sudoku Solver Hard Java 38 Count and Say Easy Java 39 Combination Sum Medium Java 40 Combination Sum II Medium Java 41 First Missing Positive Hard Java 42 Trapping Rain Water Hard Java 43 Multiply Strings Medium Java 44 Wildcard Matching Hard Java 45 Jump Game II Hard Java 46 Permutations Medium Java 47 Permutations II Medium Java 48 Rotate Image Medium Java 49 Group Anagrams Medium Java 50 Pow(x, n) Medium Java 51 N-Queens Hard Java 52 N-Queens II Hard Java 53 Maximum Subarray Easy Java 54 Spiral Matrix Medium Java 55 Jump Game Medium Java 56 Merge Intervals Medium Java 57 Insert Interval Hard Java 58 Length of Last Word Easy Java 59 Spiral Matrix II Medium Java 60 Permutation Sequence Medium Java 61 Rotate List Medium Java 62 Unique Paths Medium Java 63 Unique Paths II Medium Java 64 Minimum Path Sum Medium Java 65 Valid Number Hard Java 66 Plus One Easy Java 67 Add Binary Easy Java 68 Text Justification Hard Java 69 Sqrt(x) Easy Java 70 Climbing Stairs Easy Java 71 Simplify Path Medium Java 72 Edit Distance Hard Java 73 Set Matrix Zeroes Medium Java 74 Search a 2D Matrix Medium Java 75 Sort Colors Medium Java 76 Minimum Window Substring Hard Java 77 Combinations Medium Java 78 Subsets Medium Java 79 Word Search Medium Java 80 Remove Duplicates from Sorted Array II Medium Java 81 Search in Rotated Sorted Array II Medium Java