leetCode ... Title Solution Difficulty ... 001 Two Sum python Medium 002 Add Two Numbers python Medium 003 Longest Substring Without Repeating Characters python Medium 004 Median of Two Sorted Arrays python Hard 005 Longest Palindromic Substring python Medium 006 ZigZag Conversion python Easy 007 Reverse Integer python Easy 008 String to Integer (atoi) python Easy 009 Palindrome Number python Easy 010 Regular Expression Matching python Hard 011 Container With Most Water python Medium 012 Integer to Roman python Medium 013 Roman to Integer python Easy 014 Longest Common Prefix python Easy 015 3Sum python Medium 016 3Sum Closest python Medium 017 Letter Combinations of a Phone Number python Medium 018 4Sum python Medium 019 Remove Nth Node From End of List python Easy 020 Valid Parentheses python Easy 021 Merge Two Sorted Lists python Easy 022 Generate Parentheses python Medium 023 Merge k Sorted Lists python Hard 024 Swap Nodes in Pairs python Medium 025 Reverse Nodes in k-Group python Hard 026 Remove Duplicates from Sorted Array python Easy 027 Remove Element python Easy 028 Implement strStr() python Easy 029 Divide Two Integers python Medium 030 Substring with Concatenation of All Words python Hard 031 Next Permutation python Medium 032 Longest Valid Parentheses python Hard 033 Search in Rotated Sorted Array python Medium 034 Find First and Last Position of Element in Sorted Array python Medium 035 Search Insert Position python Medium 036 Valid Sudoku python Medium 037 Sudoku Solver python Hard 038 Count and Say python Easy 039 Combination Sum python Medium 回溯 040 Combination Sum II python Medium 回溯、贪心 041 First Missing Positive python Hard 042 Trapping Rain Water python Hard 043 Multiply Strings python Medium 044 Wildcard Matching python Medium 动态规划/贪心 045 Jump Game II python Hard 046 Permutations python Hard 全排列，递归回溯～039/040 047 Permutations II python Hard 递归回溯～039/040/046 048 Rotate Image python Medium 矩阵旋转180 049 Group Anagrams python Medium 050 Pow(x, n) python Medium 051 N-Queens python Medium 052 N-Queens II python Medium 053 Maximum Subarray python Easy 054 Spiral Matrix python Medium 055 Jump Game python Medium 056 Merge Intervals python Hard 057 Insert Interval python Hard 058 Length of Last Word python Easy 059 Spiral Matrix II python Medium 060 Permutation Sequence python Medium 061 Rotate List python Medium 062 Unique Paths python Medium 063 Unique Paths II python Medium 064 Minimum Path Sum python Medium 065 Valid Number python Hard 066 Plus One python Easy 067 Add Binary python Easy 068 Text Justification python Hard 069 Sqrt(x) python Easy 070 Climbing Stairs python Easy 071 Simplify Path python Medium 072 Edit Distance python Medium 073 Set Matrix Zeroes python Medium 094 Binary Tree Inorder Traversal python Medium 二叉树 859 Buddy Strings python Easy