Solutions to problems on LeetCode. Pages 1 2 3 # Title Solution Time Space Difficulty Note 1 Two Sum Java O(n) O(n) Easy 2 Add Two Numbers Java O(n) O(1) Easy 3 Longest Substring Without Repeating Characters Java O(n) O(n) Medium 4 Median of Two Sorted Arrays Hard 5 Longest Palindromic Substring Medium 6 ZigZag Conversion Medium 7 Reverse Integer Java O(n) O(n) Easy 8 String to Integer atoi Medium 9 Palindrome Number Easy 10 Regular Expression Matching Hard 11 Container With Most Water Medium 12 Integer to Roman Medium 13 Roman to Integer Easy 14 Longest Common Prefix Easy 15 3Sum Medium 16 3Sum Closest Medium 17 Letter Combinations of a Phone Number Medium 18 4Sum Medium 19 Remove Nth Node From End of List Medium 20 Valid Parentheses Easy 21 Merge Two Sorted Lists Easy 22 Generate Parentheses Medium 23 Merge k Sorted Lists Hard 24 Swap Nodes in Pairs Medium 25 Reverse Nodes in k-Group Hard 26 Remove Duplicates from Sorted Array Easy 27 Remove Element Easy 28 Implement strStr() Easy 29 Divide Two Integers Medium 30 Substring with Concatenation of All Words Hard 31 Next Permutation Medium 32 Longest Valid Parentheses Hard 33 Search in Rotated Sorted Array Medium 34 Search for a Range Medium 35 Search Insert Position Easy 36 Valid Sudoku Medium 37 Sudoku Solver Hard 38 Count and Say Easy 39 Combination Sum Medium 40 Combination Sum II Medium 41 First Missing Positive Hard 42 Trapping Rain Water Hard 43 Multiply Strings Medium 44 Wildcard Matching Hard 45 Jump Game II Hard 46 Permutations Medium 47 Permutations II Medium 48 Rotate Image Medium 49 Group Anagrams Medium 50 Pow(x,n) Medium Pages 1 2 3
