Leetcode 题目列表（难度、出现频率、知识点）

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