13/10/12 LeetCode Question Difficulty Distribution LeetCode  Question  Difficulty  Distribution  :  Sheet1 ID Question 1 Two Sum 2 Add Two Numbers 3 Longest Substring Without Repeating Characters 4 Median of Two Sorted Arrays 5 Longest Palindromic Substring 6 ZigZag Conversion 7 Reverse Integer 8 String to Integer (atoi) 9 Palindrome Number 10 Regular Expression Matching 11 Container With Most Water 12 Integer to Roman 13 Roman to Integer 14 Longest Common Prefix 15 3Sum 16 3Sum Closest 17 Letter Combinations of a Phone Number 18 4Sum 19 Remove Nth Node From End of List 20 Valid Parentheses 21 Merge Two Sorted Lists 22 Generate Parentheses 23 Merge k Sorted Lists 24 Swap Nodes in Pairs 25 Reverse Nodes in k-Group 26 Remove Duplicates from Sorted Array 27 Remove Element 28 Implement strStr() 29 Divide Two Integers 30 Substring with Concatenation of All Words 31 Next Permutation 32 Longest Valid Parentheses 33 Search in Rotated Sorted Array 34 Search for a Range 35 Search Insert Position 36 Valid Sudoku 37 Sudoku Solver 38 Count and Say 39 Combination Sum 40 Combination Sum II 41 First Missing Positive Diff Freq Data Structure Algorithms 2 3 3 5 4 3 2 2 2 5 3 3 2 2 3 3 3 3 2 2 2 3 3 2 4 1 1 4 4 3 5 4 4 4 2 2 4 2 3 4 5 5 array set 4 linked list 2 string hashtable 3 array 2 string 1 string 3 5 string 2 3 string 2 array 4 4 1 string 5 array 1 array 3 string 2 array 3 linked list 5 string 5 linked list 4 string 4 linked list heap 4 linked list 2 linked list 3 array 4 array 5 string 3 1 string 2 array 1 string 3 array 3 array 2 array 2 array 2 array 2 string 3 array 2 array 2 array sort Two Pointers Two Pointers Math Two Pointers Binary Search Math Math Math Recursion DP Two Pointers Math Math Two Pointers Two Pointers DFS Two Pointers Stack sort Two Pointers merge DFS sort Two Pointers merge Recursion Two Pointers Two Pointers Two Pointers Two Pointers KMP rolling hash Binary Search Math Two Pointers permutation DP Binary Search Binary Search DFS Two Pointers combination combination sort https://docs.google.com/spreadsheet/pub?key=0Aqt-- wSNYfuxdGxQWVFsOGdVVWxQRlNUVXZTdEpOeEE&output=html 1/4 

13/10/12 LeetCode Question Difficulty Distribution 42 Trapping Rain Water 43 Multiply Strings 44 Wildcard Matching 45 Jump Game II 46 Permutations 47 Permutations II 48 Rotate Image 49 Anagrams 50 Pow(x, n) 51 N-Queens 52 N-Queens II 53 Maximum Subarray 54 Spiral Matrix 55 Jump Game 56 Merge Intervals 57 Insert Interval 58 Length of Last Word 59 Spiral Matrix II 60 Permutation Sequence 61 Rotate List 62 Unique Paths 63 Unique Paths II 64 Minimum Path Sum 65 Valid Number 66 Plus One 67 Add Binary 68 Text Justification 69 Sqrt(x) 70 Climbing Stairs 71 Simplify Path 72 Edit Distance 73 Set Matrix Zeroes 74 Search a 2D Matrix 75 Sort Colors 76 Minimum Window Substring 77 Combinations 78 Subsets 79 Word Search 80 Remove Duplicates from Sorted Array II 81 Search in Rotated Sorted Array II 82 Remove Duplicates from Sorted List II 83 Remove Duplicates from Sorted List 84 Largest Rectangle in Histogram 4 4 5 4 3 4 4 3 3 4 4 3 4 3 4 4 1 3 5 3 2 3 3 2 1 2 4 4 2 3 4 3 3 4 4 3 3 3 2 5 3 1 5 2 array 3 string 3 string 2 array 4 array 2 array 2 array 4 string hashtable 5 3 array 3 array 3 array 2 array 2 array 5 array 5 array linked list red-black tree linked list red-black tree 1 string 2 array 1 2 linked list 3 array 3 array 3 array 5 string 2 array 4 string 2 string 4 5 1 string 3 string 5 array 3 array 2 array 2 string 4 4 array 4 array 2 array 3 array 3 linked list 3 linked list 2 array Two Pointers Stack Two Pointers Math Recursion DP greedy permutation permutation Binary Search Math DFS DFS DP sort merge sort merge permutation Math Two Pointers DP DP DP Math Math Two Pointers Math Binary Search DP Stack DP Binary Search sort Two Pointers Two Pointers combination Recursion combination DFS Two Pointers Binary Search Recursion Two Pointers Stack https://docs.google.com/spreadsheet/pub?key=0Aqt-- wSNYfuxdGxQWVFsOGdVVWxQRlNUVXZTdEpOeEE&output=html 2/4 

13/10/12 LeetCode Question Difficulty Distribution 85 Maximal Rectangle 86 Partition List 87 Scramble String 88 Merge Sorted Array 89 Gray Code 90 Subsets II 91 Decode Ways 92 Reverse Linked List II 93 Restore IP Addresses 94 Binary Tree Inorder Traversal 95 Unique Binary Search Trees II 96 Unique Binary Search Trees 97 Interleaving String 98 Validate Binary Search Tree 99 Recover Binary Search Tree 100 Same Tree 101 Symmetric Tree 102 Binary Tree Level Order Traversal 103 Binary Tree Zigzag Level Order Traversal 104 Maximum Depth of Binary Tree 105 Construct Binary Tree from Preorder and Inorder Tr 106 Construct Binary Tree from Inorder and Postorder T 107 Binary Tree Level Order Traversal II 108 Convert Sorted Array to Binary Search Tree 109 Convert Sorted List to Binary Search Tree 110 Balanced Binary Tree 111 Minimum Depth of Binary Tree 112 Path Sum 113 Path Sum II 114 Flatten Binary Tree to Linked List 115 Distinct Subsequences 116 Populating Next Right Pointers in Each Node 117 Populating Next Right Pointers in Each Node II 118 Pascal's Triangle 119 Pascal's Triangle II 120 Triangle 121 Best Time to Buy and Sell Stock 122 Best Time to Buy and Sell Stock II 123 Best Time to Buy and Sell Stock III 124 Binary Tree Maximum Path Sum 125 Valid Palindrome 126 Word Ladder II 127 Word Ladder 5 3 5 2 4 4 3 3 3 4 4 3 5 3 4 1 1 3 4 1 3 3 3 2 4 1 1 1 2 3 4 3 4 2 2 3 2 3 4 4 2 1 3 1 array 3 linked list 2 string 5 array 2 2 array 4 string 2 linked list 3 string 3 tree hashtable 1 tree 1 tree 2 string 5 tree 2 tree 1 tree 2 tree 4 tree 3 queue tree 1 tree 3 array tree 3 array tree 1 tree 3 tree 3 linked list 2 tree 1 tree 3 tree 2 tree 3 tree 2 string 3 tree 2 tree 1 array 1 array 1 array 1 array 1 array 1 array 2 tree 5 string 1 5 graph DP Stack Two Pointers Recursion DP Two Pointers merge combination Recursion combination Recursion DP Two Pointers DFS Recursion morris Stack DP DFS DP Recursion DP DFS DFS DFS DFS BFS BFS Stack DFS DFS DFS BFS DFS Recursion Two Pointers DFS DFS DFS DFS Recursion Stack DP DFS DFS DP DP greedy DP DFS Two Pointers BFS shortest path https://docs.google.com/spreadsheet/pub?key=0Aqt-- wSNYfuxdGxQWVFsOGdVVWxQRlNUVXZTdEpOeEE&output=html 3/4 

13/10/12 LeetCode Question Difficulty Distribution 128 Longest Consecutive Sequence 129 Sum Root to Leaf Numbers 130 Surrounded Regions 4 2 4 131 Palindrome Partitioning 132 Palindrome Partitioning II 3 4 由  Google  云端硬盘发布   –  举报滥用行为   –  每  5  分钟进行自动更新 3 array 4 tree 3 array 4 string 3 string shortest path DFS BFS DFS DFS DP https://docs.google.com/spreadsheet/pub?key=0Aqt-- wSNYfuxdGxQWVFsOGdVVWxQRlNUVXZTdEpOeEE&output=html 4/4