参考：https://blog.csdn.net/qq_39521554/article/details/79160815

二、刷题方法

方法一：按照题目出现频率刷题

顺序参考文章最后的部分

方法二：标签法
按照网站给大家排列的不同tags，起到模块化的复习和学习作用。举个例子：比如复习链表的内容，就选Linked List这部分的23个题目。刷完之后可以再总结一下常用的方法和数据结构与构造方式。请不要为了刷题而刷题，一定是为了弥补一部分的知识去做。

方法三：随机法
随心所欲的选择难度与刷题顺序，哪个顺眼做哪个。本方法只适合业余编程，不从事本行业的同学以及大神级人物

方法四：必杀法
leetcode是有公司题库的，一句话：面哪家，刷哪家

方法五：顺序法
建议未刷过题的新人按着顺序（AC）来。前 150 题覆盖了很多经典题目和知识点，指针法类如『3 sum』系列，动规类如『regex matching』，搜索类题目如『Sodoku Solver』。

基本熟悉知识点（图、树、堆、栈、链表、哈希表、记忆搜索、动态规划、指针法、并查集等）后，可以一类类标签强攻。Leetcode 右侧的标签系统虽然未必 100% 完整，但是大致分类做得还不错。

面试前的一个月可以只做『Hard』标签的题目，因为一般两遍之后对于大部分『Medium』难度以下的题目都是肌肉记忆了。多练习『Hard』类题目可以让自己的思路更开阔，因为很多题目使用的奇淫巧技让人惊讶，比如 Leetcode 精心设计连续题号的『84. Largest Rectangle in Histogram』、『85. Maximal Rectangle』。

三、刷题攻略
TIP 1：

对于大多数人来说，没有时间也没有必要把所有题目都做一遍（时间充裕可以随意）。

可以考虑序号为前250位的题目，因为那些全是经典与必考题。

TIP 2：

善用收藏夹，要养成『一道题第二次练习尚不能解就加入收藏夹』的习惯，且需要定期清空收藏夹：每道题不需提示下通过两次后才能移出收藏夹。

TIP 3：

可以按照下文的面试出题频率顺序来做，从频率最高的一批开始。 而且请尽量不使用IDE，直接在平台上写代码。 

面试前可以购买会员，按照公司的标签来练习，也可以结合白板练习。面试前如果时间紧迫，那么练习的优先级分别是：即将面试公司的题目、收藏夹里的旧题目、剩余的新题。

冲刺阶段的练习请尽量不要打开题型标签，给自己思考的空间。如果真的刷了三遍以上还没法达到理想目标，那么一定是学习方法出了问题，请多总结。

TIP 4：
写好代码先不要提交，人工检查一下代码，比如分号是否都有写，return有没少等。 人工检查完后使用“Custom Testcase”功能自定义测试用例，注意检查边界，然后“Run Code”，这步可以发现蛮多问题的。  等RunCode通过后，再去提交。

————

Top 100个题目：https://leetcode.com/problemset/top-100-liked-questions/

---

 

#

Title

Solution

Acceptance

Difficulty

Frequency

 

1

Two Sum    

 

40.2%

Easy

 

 

2

Add Two Numbers    

 

30.4%

Medium

 

 

3

Longest Substring Without Repeating Characters    

 

26.1%

Medium

 

 

4

Median of Two Sorted Arrays    

 

25.3%

Hard

 

 

5

Longest Palindromic Substring    

 

26.4%

Medium

 

 

10

Regular Expression Matching    

 

24.9%

Hard

 

 

11

Container With Most Water    

 

42.1%

Medium

 

 

15

3Sum    

 

23.2%

Medium

 

 

17

Letter Combinations of a Phone Number    

 

40.1%

Medium

 

 

19

Remove Nth Node From End of List    

 

33.9%

Medium

 

 

20

Valid Parentheses    

 

35.7%

Easy

 

 

21

Merge Two Sorted Lists    

 

45.5%

Easy

 

 

22

Generate Parentheses    

 

52.8%

Medium

 

 

23

Merge k Sorted Lists    

 

32.6%

Hard

 

 

31

Next Permutation    

 

30.0%

Medium

 

 

32

Longest Valid Parentheses    

 

24.8%

Hard

 

 

33

Search in Rotated Sorted Array    

 

32.6%

Medium

 

 

34

Find First and Last Position of Element in Sorted Array    

 

32.8%

Medium

 

 

39

Combination Sum    

 

46.3%

Medium

 

 

42

Trapping Rain Water    

 

41.5%

Hard

 

 

46

Permutations    

 

53.0%

Medium

 

 

48

Rotate Image    

 

46.4%

Medium

 

 

49

Group Anagrams    

 

44.3%

Medium

 

 

53

Maximum Subarray    

 

42.6%

Easy

 

 

55

Jump Game    

 

31.1%

Medium

 

 

56

Merge Intervals    

 

34.6%

Medium

 

 

62

Unique Paths    

 

46.1%

Medium

 

 

64

Minimum Path Sum    

 

45.2%

Medium

 

 

70

Climbing Stairs    

 

43.2%

Easy

 

 

72

Edit Distance    

 

36.2%

Hard

 

 

75

Sort Colors    

 

41.1%

Medium

 

 

76

Minimum Window Substring    

 

29.6%

Hard

 

 

78

Subsets    

 

50.5%

Medium

 

 

79

Word Search    

 

30.2%

Medium

 

 

84

Largest Rectangle in Histogram    

 

30.1%

Hard

 

 

85

Maximal Rectangle    

 

32.2%

Hard

 

 

94

Binary Tree Inorder Traversal    

 

54.7%

Medium

 

 

96

Unique Binary Search Trees    

 

44.8%

Medium

 

 

98

Validate Binary Search Tree    

 

25.1%

Medium

 

 

101

Symmetric Tree    

 

42.5%

Easy

 

 

102

Binary Tree Level Order Traversal    

 

46.7%

Medium

 

 

104

Maximum Depth of Binary Tree    

 

58.9%

Easy

 

 

105

Construct Binary Tree from Preorder and Inorder Traversal    

 

39.1%

Medium

 

 

114

Flatten Binary Tree to Linked List    

 

40.8%

Medium

 

 

121

Best Time to Buy and Sell Stock    

 

46.0%

Easy

 

 

124

Binary Tree Maximum Path Sum    

 

29.1%

Hard

 

 

128

Longest Consecutive Sequence    

 

40.7%

Hard

 

 

136

Single Number    

 

58.7%

Easy

 

 

139

Word Break    

 

34.1%

Medium

 

 

141

Linked List Cycle    

 

35.5%

Easy

 

#

Title

Solution

Acceptance

Difficulty

Frequency

 

142

Linked List Cycle II    

 

30.7%

Medium

 

 

146

LRU Cache    

 

23.7%

Hard

 

 

148

Sort List    

 

33.6%

Medium

 

 

152

Maximum Product Subarray    

 

28.4%

Medium

 

 

155

Min Stack    

 

35.3%

Easy

 

 

160

Intersection of Two Linked Lists    

 

31.9%

Easy

 

 

169

Majority Element    

 

51.2%

Easy

 

 

198

House Robber    

 

40.7%

Easy

 

 

200

Number of Islands    

 

40.0%

Medium

 

 

206

Reverse Linked List    

 

52.3%

Easy

 

 

207

Course Schedule    

 

36.4%

Medium

 

 

208

Implement Trie (Prefix Tree)    

 

36.4%

Medium

 

 

215

Kth Largest Element in an Array    

 

45.5%

Medium

 

 

221

Maximal Square    

 

32.1%

Medium

 

 

226

Invert Binary Tree    

 

56.8%

Easy

 

 

234

Palindrome Linked List    

 

35.2%

Easy

 

 

236

Lowest Common Ancestor of a Binary Tree    

 

35.0%

Medium

 

 

238

Product of Array Except Self    

 

53.6%

Medium

 

 

239

Sliding Window Maximum    

 

36.8%

Hard

 

 

240

Search a 2D Matrix II    

 

40.1%

Medium

 

 

253

Meeting Rooms II    

 

41.9%

Medium

 

 

279

Perfect Squares    

 

40.4%

Medium

 

 

283

Move Zeroes    

 

53.4%

Easy

 

 

287

Find the Duplicate Number    

 

48.0%

Medium

 

 

297

Serialize and Deserialize Binary Tree    

 

39.0%

Hard

 

 

300

Longest Increasing Subsequence    

 

40.1%

Medium

 

 

301

Remove Invalid Parentheses    

 

38.2%

Hard

 

 

309

Best Time to Buy and Sell Stock with Cooldown    

 

43.4%

Medium

 

 

312

Burst Balloons    

 

46.0%

Hard

 

 

322

Coin Change    

 

28.8%

Medium

 

 

337

House Robber III    

 

47.1%

Medium

 

 

338

Counting Bits    

 

63.8%

Medium

 

 

347

Top K Frequent Elements    

 

53.1%

Medium

 

 

394

Decode String    

 

43.6%

Medium

 

 

406

Queue Reconstruction by Height    

 

58.7%

Medium

 

 

416

Partition Equal Subset Sum    

 

39.7%

Medium

 

 

437

Path Sum III    

 

41.8%

Easy

 

 

438

Find All Anagrams in a String    

 

36.1%

Easy

 

 

448

Find All Numbers Disappeared in an Array    

 

52.6%

Easy

 

 

461

Hamming Distance    

 

70.0%

Easy

 

 

494

Target Sum    

 

44.8%

Medium

 

 

538

Convert BST to Greater Tree    

 

49.8%

Easy

 

 

543

Diameter of Binary Tree    

 

46.1%

Easy

 

 

560

Subarray Sum Equals K    

 

41.5%

Medium

 

 

572

Subtree of Another Tree    

 

41.1%

Easy

 

 

581

Shortest Unsorted Continuous Subarray    

 

29.6%

Easy

 

 

617

Merge Two Binary Trees    

 

69.0%

Easy

 

 

621

Task Scheduler    

 

44.1%

Medium

 

 

647

Palindromic Substrings    

 

55.5%

Medium

 

 

771

Jewels and Stones    

 

82.6%

Easy

出现频度为5： 
1. Leet Code OJ 1. Two Sum [Difficulty: Easy] 
2. Leet Code OJ 8. String to Integer (atoi) [Difficulty: Easy] 
3. Leet Code OJ 15. 3Sum [Difficulty: Medium] 
4. Leet Code OJ 20. Valid Parentheses [Difficulty: Easy] 
5. Leet Code OJ 21. Merge Two Sorted Lists [Difficulty: Easy] 
6. Leet Code OJ 28. Implement strStr() [Difficulty: Easy] 
7. Leet Code OJ 56. Merge Intervals [Difficulty: Hard] 
8. Leet Code OJ 57. Insert Interval [Difficulty: Hard] 
9. Leet Code OJ 65. Valid Number [Difficulty: Hard] 
10. Leet Code OJ 70. Climbing Stairs [Difficulty: Easy] 
11. Leet Code OJ 73. Set Matrix Zeroes [Difficulty: Medium] 
12. Leet Code OJ 88. Merge Sorted Array [Difficulty: Easy] 
13. Leet Code OJ 98. Validate Binary Search Tree [Difficulty: Medium] 
14. Leet Code OJ 125. Valid Palindrome [Difficulty: Easy] 
15. Leet Code OJ 127. Word Ladder [Difficulty: Medium]

出现频度为4： 
1. Leet Code OJ 2. Add Two Numbers [Difficulty: Medium] 
2. Leet Code OJ 12. Integer to Roman 
3. Leet Code OJ 13. Roman to Integer 
4. Leet Code OJ 22. Generate Parentheses 
5. Leet Code OJ 23. Merge k Sorted Lists 
6. Leet Code OJ 24. Swap Nodes in Pairs 
7. Leet Code OJ 27. Remove Element [Difficulty: Easy] 
8. Leet Code OJ 46. Permutations 
9. Leet Code OJ 49. Anagrams 
10. Leet Code OJ 67. Add Binary 
11. Leet Code OJ 69. Sqrt(x) 
12. Leet Code OJ 77. Combinations 
13. Leet Code OJ 78. Subsets 
14. Leet Code OJ 79. Word Search 
15. Leet Code OJ 91. Decode Ways [Difficulty: Medium] 
16. Leet Code OJ 102. Binary Tree Level Order Traversal [Difficulty: Easy] 
17. Leet Code OJ 129. Sum Root to Leaf Numbers 
18. Leet Code OJ 131. Palindrome Partitioning