LeetCode题目索引-难度及面试频率

LeetCode题目索引-难度及面试频率

             

 

ID 问题 难度 面试频率 数据结构 算法  
               
             

 

1 Two Sum 2 5 array sort

 

        set Two Pointers

 

2 Add Two Numbers 3 4 linked list Two Pointers

 

          Math

 

3 Longest Substring Without Repeating Characters 3 2 string Two Pointers

 

        hashtable  

 

4 Median of Two Sorted Arrays 5 3 array Binary Search

 

5 Longest Palindromic Substring 4 2 string  

 

6 ZigZag Conversion 3 1 string  

 

7 Reverse Integer 2 3   Math

 

8 String to Integer (atoi) 2 5 string Math

 

9 Palindrome Number 2 2   Math

 

10 Regular Expression Matching 5 3 string Recursion

 

          DP

 

11 Container With Most Water 3 2 array Two Pointers

 

12 Integer to Roman 3 4   Math

 

13 Roman to Integer 2 4   Math

 

14 Longest Common Prefix 2 1 string  

 

15 3Sum 3 5 array Two Pointers

 

16 3Sum Closest 3 1 array Two Pointers

 

17 Letter Combinations of a Phone Number 3 3 string DFS

 

18 4Sum 3 2 array  

 

19 Remove Nth Node From End of List 2 3 linked list Two Pointers

 

20 Valid Parentheses 2 5 string Stack

 

21 Merge Two Sorted Lists 2 5 linked list sort

 

          Two Pointers

 

          merge

 

22 Generate Parentheses 3 4 string DFS

 

23 Merge k Sorted Lists 3 4 linked list sort

 

        heap Two Pointers

 

          merge

 

24 Swap Nodes in Pairs 2 4 linked list  

 

25 Reverse Nodes in k-Group 4 2 linked list Recursion

 

          Two Pointers

 

26 Remove Duplicates from Sorted Array 1 3 array Two Pointers

 

27 Remove Element 1 4 array Two Pointers

 

28 Implement strStr() 4 5 string Two Pointers

 

          KMP

 

          rolling hash

 

29 Divide Two Integers 4 3   Binary Search

 

          Math

 

30 Substring with Concatenation of All Words 3 1 string Two Pointers

 

31 Next Permutation 5 2 array permutation

 

32 Longest Valid Parentheses 4 1 string DP

 

33 Search in Rotated Sorted Array 4 3 array Binary Search

 

34 Search for a Range 4 3 array Binary Search

 

35 Search Insert Position 2 2 array  

 

36 Valid Sudoku 2 2 array  

 

37 Sudoku Solver 4 2 array DFS

 

38 Count and Say 2 2 string Two Pointers

 

39 Combination Sum 3 3 array combination

 

40 Combination Sum II 4 2 array combination

 

41 First Missing Positive 5 2 array sort

 

42 Trapping Rain Water 4 2 array Two Pointers

 

          Stack

 

43 Multiply Strings 4 3 string Two Pointers

 

          Math

 

44 Wildcard Matching 5 3 string Recursion

 

          DP

 

          greedy

 

45 Jump Game II 4 2 array  

 

46 Permutations 3 4 array permutation

 

47 Permutations II 4 2 array permutation

 

48 Rotate Image 4 2 array  

 

49 Anagrams 3 4 string  

 

        hashtable  

 

50 Pow(x, n) 3 5   Binary Search

 

          Math

 

51 N-Queens 4 3 array DFS

 

52 N-Queens II 4 3 array DFS

 

53 Maximum Subarray 3 3 array DP

 

54 Spiral Matrix 4 2 array  

 

55 Jump Game 3 2 array  

 

56 Merge Intervals 4 5 array sort

 

        linked list merge

 

        red-black tree  

 

57 Insert Interval 4 5 array sort

 

        linked list merge

 

        red-black tree  

 

58 Length of Last Word 1 1 string  

 

59 Spiral Matrix II 3 2 array  

 

60 Permutation Sequence 5 1   permutation

 

          Math

 

61 Rotate List 3 2 linked list Two Pointers

 

62 Unique Paths 2 3 array DP

 

63 Unique Paths II 3 3 array DP

 

64 Minimum Path Sum 3 3 array DP

 

65 Valid Number 2 5 string Math

 

66 Plus One 1 2 array Math

 

67 Add Binary 2 4 string Two Pointers

 

          Math

 

68 Text Justification 4 2 string  

 

69 Sqrt(x) 4 4   Binary Search

 

70 Climbing Stairs 2 5   DP

 

71 Simplify Path 3 1 string Stack

 

72 Edit Distance 4 3 string DP

 

73 Set Matrix Zeroes 3 5 array  

 

74 Search a 2D Matrix 3 3 array Binary Search

 

75 Sort Colors 4 2 array sort

 

          Two Pointers

 

76 Minimum Window Substring 4 2 string Two Pointers

 

77 Combinations 3 4   combination

 

78 Subsets 3 4 array Recursion

 

          combination

 

79 Word Search 3 4 array DFS

 

80 Remove Duplicates from Sorted Array II 2 2 array Two Pointers

 

81 Search in Rotated Sorted Array II 5 3 array Binary Search

 

82 Remove Duplicates from Sorted List II 3 3 linked list Recursion

 

          Two Pointers

 

83 Remove Duplicates from Sorted List 1 3 linked list  

 

84 Largest Rectangle in Histogram 5 2 array Stack

 

85 Maximal Rectangle 5 1 array DP

 

          Stack

 

86 Partition List 3 3 linked list Two Pointers

 

87 Scramble String 5 2 string Recursion

 

          DP

 

88 Merge Sorted Array 2 5 array Two Pointers

 

          merge

 

89 Gray Code 4 2   combination

 

90 Subsets II 4 2 array Recursion

 

          combination

 

91 Decode Ways 3 4 string Recursion

 

          DP

 

92 Reverse Linked List II 3 2 linked list Two Pointers

 

93 Restore IP Addresses 3 3 string DFS

 

94 Binary Tree Inorder Traversal 4 3 tree Recursion

 

        hashtable morris

 

          Stack

 

95 Unique Binary Search Trees II 4 1 tree DP

 

          DFS

 

96 Unique Binary Search Trees 3 1 tree DP

 

97 Interleaving String 5 2 string Recursion

 

          DP

 

98 Validate Binary Search Tree 3 5 tree DFS

 

99 Recover Binary Search Tree 4 2 tree DFS

 

100 Same Tree 1 1 tree DFS

 

101 Symmetric Tree 1 2 tree DFS

 

102 Binary Tree Level Order Traversal 3 4 tree BFS

 

103 Binary Tree Zigzag Level Order Traversal 4 3 queue BFS

 

        tree Stack

 

104 Maximum Depth of Binary Tree 1 1 tree DFS

 

105 Construct Binary Tree from Preorder and Inorder Tr 3 3 array DFS

 

        tree  

 

106 Construct Binary Tree from Inorder and Postorder T 3 3 array DFS

 

        tree  

 

107 Binary Tree Level Order Traversal II 3 1 tree BFS

 

108 Convert Sorted Array to Binary Search Tree 2 3 tree DFS

 

109 Convert Sorted List to Binary Search Tree 4 3 linked list Recursion

 

          Two Pointers

 

110 Balanced Binary Tree 1 2 tree DFS

 

111 Minimum Depth of Binary Tree 1 1 tree DFS

 

112 Path Sum 1 3 tree DFS

 

113 Path Sum II 2 2 tree DFS

 

114 Flatten Binary Tree to Linked List 3 3 tree Recursion

 

          Stack

 

115 Distinct Subsequences 4 2 string DP

 

116 Populating Next Right Pointers in Each Node 3 3 tree DFS

 

117 Populating Next Right Pointers in Each Node II 4 2 tree DFS

 

118 Pascal's Triangle 2 1 array  

 

119 Pascal's Triangle II 2 1 array  

 

120 Triangle 3 1 array DP

 

121 Best Time to Buy and Sell Stock 2 1 array DP

 

122 Best Time to Buy and Sell Stock II 3 1 array greedy

 

123 Best Time to Buy and Sell Stock III 4 1 array DP

 

124 Binary Tree Maximum Path Sum 4 2 tree DFS

 

125 Valid Palindrome 2 5 string Two Pointers

 

126 Word Ladder II 1 1    

 

127 Word Ladder 3 5 graph BFS

 

          shortest path

 

128 Longest Consecutive Sequence 4 3 array  

 

129 Sum Root to Leaf Numbers 2 4 tree DFS

 

130 Surrounded Regions 4 3 array BFS

 

          DFS

 

131 Palindrome Partitioning 3 4 string DFS

 

132 Palindrome Partitioning II 4 3 string DP