LeetCode4FLAG

High frequent interview LeetCode test for FaceBook, Linkedin, Amazon, Google. More importantly, the problems' solutions are provided in C/C++, Python and Java. Offer, Offer, Offer !

高频合集 • 答题模板 • 打卡群 • 📕 Docs

Note: Please raise an issue for any suggestions, corrections, and feedback.

Index

🔥 Top100
💠 Classification
📕 算法思维+算法模板
📂 面经C++/后端/算法
👥 Community
💖 Support

Top100

Company	Level	LeetCode Link	Code	✅ AC
	Easy	✂️ 74. Search a 2D Matrix	C++ \| 🐍 Python \| ♨️ Java	2021-09-30
		🐼 1. Two Sum	C++ \| 🐍 Python \| ♨️ Java
		📈 21. Merge Two Sorted Lists	C++ \| 🐍 Python \| ♨️ Java
		🔎 107. Binary Tree Level Order Traversal II	C++ \| 🐍 Python \| ♨️ Java
		👑 32. Longest Valid Parentheses	C++ \| 🐍 Python \| ♨️ Java
		🎡 20. Valid Parentheses	C++ \| 🐍 Python \| ♨️ Java
		🌄 200. Number of Islands	C++ \| 🐍 Python \| ♨️ Java
		🐋 202. Happy Number	C++ \| 🐍 Python \| ♨️ Java
		🐑 1120. Maximum Average Subtree	C++ \| 🐍 Python \| ♨️ Java
		🐧 543. Diameter of Binary Tree	C++ \| 🐍 Python \| ♨️ Java
	Medium
		⛺ 297. Serialize and Deserialize Binary Tree	C++ \| 🐍 Python \| ♨️ Java
		🌈 240. Search a 2D Matrix II	C++ \| 🐍 Python \| ♨️ Java
		🚀 124. Binary Tree Maximum Path Sum	C++ \| 🐍 Python \| ♨️ Java
	Hard
		⛺ 297. Serialize and Deserialize Binary Tree	C++ \| 🐍 Python \| ♨️ Java
		🌈 240. Search a 2D Matrix II	C++ \| 🐍 Python \| ♨️ Java
	Easy	🚠 94. Binary Tree Inorder Traversal	C++ \| 🐍 Python \| ♨️ Java
		⛵ 863. All Nodes Distance K in Binary Tree	C++ \| 🐍 Python \| ♨️ Java
		📈 21. Merge Two Sorted Lists	C++ \| 🐍 Python \| ♨️ Java
		🔎 107. Binary Tree Level Order Traversal II	C++ \| 🐍 Python \| ♨️ Java
		👑 32. Longest Valid Parentheses	C++ \| 🐍 Python \| ♨️ Java
		🎡 20. Valid Parentheses	C++ \| 🐍 Python \| ♨️ Java
		🌄 200. Number of Islands	C++ \| 🐍 Python \| ♨️ Java
		🐋 202. Happy Number	C++ \| 🐍 Python \| ♨️ Java
		🐑 1120. Maximum Average Subtree	C++ \| 🐍 Python \| ♨️ Java
		🐏 543. Diameter of Binary Tree	C++ \| 🐍 Python \| ♨️ Java
	Medium
		⛵ 494. Target Sum	C++ \| 🐍 Python \| ♨️ Java
		🚁 938. Range Sum of BST	C++ \| 🐍 Python \| ♨️ Java
		🚀 124. Binary Tree Maximum Path Sum	C++ \| 🐍 Python \| ♨️ Java
	Hard
		⛺ 173. Binary Search Tree Iterator	C++ \| 🐍 Python \| ♨️ Java
		🌈 239. Sliding Window Maximum	C++ \| 🐍 Python \| ♨️ Java
	Easy	🚠 833. Find And Replace in String	C++ \| 🐍 Python \| ♨️ Java
		🌄 200. Number of Islands	C++ \| 🐍 Python \| ♨️ Java
		🐠 67. Add Binary	C++ \| 🐍 Python \| ♨️ Java
	Medium
		🚩 90. Subsets II	C++ \| 🐍 Python \| ♨️ Java
		🍐 17. Letter Combinations of a Phone Number	C++ \| 🐍 Python \| ♨️ Java
		🚁 525. Contiguous Array	C++ \| 🐍 Python \| ♨️ Java
	Hard
		🎄 126. Word Ladder II	C++ \| 🐍 Python \| ♨️ Java
		🎑 85. Maximal Rectangle	C++ \| 🐍 Python \| ♨️ Java
	Easy	🎏 152. Maximum Product Subarray	C++ \| 🐍 Python \| ♨️ Java
	Easy	🍋 678. Valid Parenthesis String	C++ \| 🐍 Python \| ♨️ Java
	Medium
		⛵ 245. Shortest Word Distance III	C++ \| 🐍 Python \| ♨️ Java
		🚁 178. Rank Scores	C++ \| 🐍 Python \| ♨️ Java
	Hard
		⛺ 173. Binary Search Tree Iterator	C++ \| 🐍 Python \| ♨️ Java
		🌈 239. Sliding Window Maximum	C++ \| 🐍 Python \| ♨️ Java
	Easy	🎑 215. Kth Largest Element in an Array	C++ \| 🐍 Python \| ♨️ Java
	Easy	🍋 678. Valid Parenthesis String	C++ \| 🐍 Python \| ♨️ Java
	Medium
		⛵ 236. Lowest Common Ancestor of a Binary Tree	C++ \| 🐍 Python \| ♨️ Java
		🚁 剑指 Offer 51. 数组中的逆序对	C++ \| 🐍 Python \| ♨️ Java
	Hard
		⛺ 99. Recover Binary Search Tree	C++ \| 🐍 Python \| ♨️ Java
		🌈 239. Sliding Window Maximum	C++ \| 🐍 Python \| ♨️ Java

Index

Classification

Algorithm	LeetCode Link	Level	Code	✅ AC
Dynamic Programming 动态规划 --> 解题模板
	⛺ 568. Maximum Vacation Days	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🌈 70. Climbing Stairs	⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🚀 10. Regular Expression Matching	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	⛺ 198. House Robber	⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🌈 139. Word Break	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🎏 152. Maximum Product Subarray	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🌈 91. Decode Ways	⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 72. Edit Distance	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
Divide & Conquer 分治思想 --> 解题模板	✂️ 4. Median of Two Sorted Arrays	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 23. Merge k Sorted Lists	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 110. Balanced Binary Tree	⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🚀 124. Binary Tree Maximum Path Sum	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 98. Validate Binary Search Tree	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
Dichotomy 二分法 --> 解题模板	✂️ 153. Find Minimum in Rotated Sorted Array	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 33. Search in Rotated Sorted Array	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 69. Sqrt(x)	⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🔎 29. Divide Two Integers	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 162. Find Peak Element	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
Recursion 递归 --> 解题模板	✂️ 22. 括号生成	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 89. 格雷编码	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 110. 平衡二叉树	⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 17. 电话号码的字母组合	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 46. 全排列	⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🔎 124. 二叉树中的最大路径和	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
Sorting Algorithm 排序算法 --> 解题模板	✂️ 215. 数组中的第K个最大元素	⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 LintCode. 无序数组K小元素	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 629. K个逆序对数组	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 剑指 Offer 51. 数组中的逆序对	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 327. 区间和的个数	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🔎 LintCode 399.Nuts & Bolts Problem-Nuts 和 Bolts 的问题	⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 899. 有序队列	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🔎 376. 摆动序列	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
Traverse/Visit 遍历 --> 解题模板	✂️ 123. 买卖股票的最佳时机 III	⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 644. 最大子段和 II	⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 102. 二叉树的层序遍历	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 144. 二叉树的前序遍历	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 145. 二叉树的后序遍历	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🔎 987. 二叉树的垂序遍历	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🔎 257. 二叉树的所有路径	⭐⭐	C++ \| 🐍 Python \| ♨️ Java
Dual Pointer Algorithm 双指针算法 --> 解题模板	✂️ 剑指 Offer 48. 最长不含重复字符的子字符串	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 11. 盛最多水的容器	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 42. 接雨水	⭐⭐⭐ #双指针-two-pointers	C++ \| 🐍 Python \| ♨️ Java
	📈 647. 回文子串	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	✂️ 92. 反转链表 II	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🔎 142. 环形链表 II	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
Breadth First Search 宽度/广度优先搜索 --> 解题模板	✂️ 127. 单词接龙	⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 200. 岛屿数量	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 102. 二叉树的层序遍历	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 133. 克隆图	⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 107. 二叉树的层序遍历 II	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🔎 199. 二叉树的右视图	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
Depth First Search 深度优先搜索 --> 解题模板	✂️ 111. 二叉树的最小深度	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🐼 面试题 05.01. 插入	⭐⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 126. 单词接龙 II	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 131. 分割回文串	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	📈 51. N 皇后	⭐⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java
	🔎 107. Binary Tree Level Order Traversal II	⭐⭐⭐	C++ \| 🐍 Python \| ♨️ Java

Index

算法思维+算法模板

回溯

result = []
def backtrack(路径, 选择列表):
    if 满足结束条件:
        result.add(路径)
        return
    for 选择 in 选择列表:
        做选择
        backtrack(路径, 选择列表)
        撤销选择

LeetCode 22. Generate Parentheses https://leetcode-cn.com/problems/generate-parentheses/

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

Example 1:

Input: n = 3
Output: ["((()))","(()())","(())()","()(())","()()()"]

Example 2:

Input: n = 1
Output: ["()"]

Constraints:

1 <= n <= 8

void backtrack(int n, int i, string& track) {
    // i 代表当前的位置，共 2n 个位置
    // 穷举到最后一个位置了，得到一个长度为 2n 组合
    if (i == 2 * n) {
        print(track);
        return;
    }
    // 对于每个位置可以是左括号或者右括号两种选择
    for choice in ['(', ')'] {
        track.push(choice); // 做选择
        // 穷举下一个位置
        backtrack(n, i + 1, track);
        track.pop(choice); // 撤销选择
    }
}

See more -> 题解模板.md

Index

Community

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Index

License

Index

🚀 知识星球

专为求职面试中算法与数据结构的小伙伴，创了学习交流/刷题群（知识星球）！想要最快的提升算法与数据结构技能，和更多小伙伴一起来吧！进阶面试八股文，大厂面经

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Name		Name	Last commit message	Last commit date
Latest commit History 406 Commits
.xet		.xet
001. Two Sum		001. Two Sum
003. Longest Substring Without Repeating Characters		003. Longest Substring Without Repeating Characters
004. Median of Two Sorted Arrays		004. Median of Two Sorted Arrays
010. Regular Expression Matching		010. Regular Expression Matching
017. Letter Combinations of a Phone Number		017. Letter Combinations of a Phone Number
020. Valid Parentheses		020. Valid Parentheses
021. Merge Two Sorted Lists		021. Merge Two Sorted Lists
022. Generate Parentheses		022. Generate Parentheses
023. Merge k Sorted Lists		023. Merge k Sorted Lists
029. Divide Two Integers		029. Divide Two Integers
032. Longest Valid Parentheses		032. Longest Valid Parentheses
033. Search in Rotated Sorted Array		033. Search in Rotated Sorted Array
067. Add Binary		067. Add Binary
069. Sqrt(x)		069. Sqrt(x)
070. Climbing Stairs		070. Climbing Stairs
072. Edit Distance		072. Edit Distance
074. Search a 2D Matrix		074. Search a 2D Matrix
076. Minimum Window Substring		076. Minimum Window Substring
085. Maximal Rectangle		085. Maximal Rectangle
090. Subsets II		090. Subsets II
091. Decode Ways		091. Decode Ways
094. Binary Tree Inorder Traversal		094. Binary Tree Inorder Traversal
098. Validate Binary Search Tree		098. Validate Binary Search Tree
099. Recover Binary Search Tree		099. Recover Binary Search Tree
107. Binary Tree Level Order Traversal II		107. Binary Tree Level Order Traversal II
110. Balanced Binary Tree		110. Balanced Binary Tree
1120. Maximum Average Subtree		1120. Maximum Average Subtree
124. Binary Tree Maximum Path Sum		124. Binary Tree Maximum Path Sum
126. Word Ladder II		126. Word Ladder II
139. Word Break		139. Word Break
146. LRU Cache		146. LRU Cache
152. Maximum Product Subarray		152. Maximum Product Subarray
153. Find Minimum in Rotated Sorted Array		153. Find Minimum in Rotated Sorted Array
162. Find Peak Element		162. Find Peak Element
173. Binary Search Tree Iterator		173. Binary Search Tree Iterator
178. Rank Scores		178. Rank Scores
198. House Robber		198. House Robber
200. Number of Islands		200. Number of Islands
202. Happy Number		202. Happy Number
215. Kth Largest Element in an Array		215. Kth Largest Element in an Array
236. Lowest Common Ancestor of a Binary Tree		236. Lowest Common Ancestor of a Binary Tree
239. Sliding Window Maximum		239. Sliding Window Maximum
240. Search a 2D Matrix II		240. Search a 2D Matrix II
245. Shortest Word Distance III		245. Shortest Word Distance III
297. Serialize and Deserialize Binary Tree		297. Serialize and Deserialize Binary Tree
468. Validate IP Address		468. Validate IP Address
494. Target Sum		494. Target Sum
525. Contiguous Array		525. Contiguous Array
543. Diameter of Binary Tree		543. Diameter of Binary Tree
568. Maximum Vacation Days		568. Maximum Vacation Days
678. Valid Parenthesis String		678. Valid Parenthesis String
833. Find And Replace in String		833. Find And Replace in String
863. All Nodes Distance K in Binary Tree		863. All Nodes Distance K in Binary Tree
938. Range Sum of BST		938. Range Sum of BST
.gitattributes		.gitattributes
2020最新-FLAMG面试频率最高的127道题.xlsx		2020最新-FLAMG面试频率最高的127道题.xlsx
CHANGLOG.md		CHANGLOG.md
CONTRIBUTING.md		CONTRIBUTING.md
FLAG.jpg		FLAG.jpg
Facebook高频题100道.xls		Facebook高频题100道.xls
Google最常考的40道动态规划题.xlsx		Google最常考的40道动态规划题.xlsx
README.md		README.md
题解模板.md		题解模板.md

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