leetcode: LeetCode Solutions: A Record of My Problem Solving Journey.( leetcode题解，记录自己的leetcode解题之路。)

# LeetCode

简体中文 | [English](./README.en.md)

---

![leetcode.jpeg](./assets/leetcode.jpeg)

## 介绍

leetcode 题解，记录自己的 leetcode 解题之路。

本仓库目前分为四个部分：

- 第一个部分是 leetcode 经典题目的解析，包括思路，关键点和具体的代码实现。

- 第二部分是对于数据结构与算法的总结

- 第三部分是 anki 卡片， 将 leetcode 题目按照一定的方式记录在 anki 中，方便大家记忆。

- 第四部分是计划， 这里会记录将来要加入到以上三个部分内容

> 只有熟练掌握基础的数据结构与算法，才能对复杂问题迎刃有余。

## 食用指南

- 对于最近添加的部分， 后面会有 🆕 标注
- 对于最近更新的部分， 后面会有 🖊 标注
- 将来会在这里更新anki卡片
- 这里有一份leetcode官方账号在知乎上给出的一个《互联网公司最常见的面试算法题有哪些？》的答案，我这里尽量去覆盖回答中的题目和知识点
原文地址： https://www.zhihu.com/question/24964987/answer/586425979

- 这里有一张互联网公司面试中经常考察的问题类型总结的思维导图，我们可以结合图片中的信息分析一下。

![leetcode-zhihu](./assets//leetcode-zhihu.jpg)

(图片来自leetcode)

其中算法，主要是以下几种：

- 基础技巧：分治、二分、贪心
- 排序算法：快速排序、归并排序、计数排序
- 搜索算法：回溯、递归、深度优先遍历，广度优先遍历，二叉搜索树等
- 图论：最短路径、最小生成树
- 动态规划：背包问题、最长子序列

数据结构，主要有如下几种：

- 数组与链表：单 / 双向链表
- 栈与队列
- 哈希表
- 堆：最大堆 ／ 最小堆
- 树与图：最近公共祖先、并查集
- 字符串：前缀树（字典树） ／ 后缀树

## 精彩预告

[0042.trapping-rain-water](./problems/42.trapping-rain-water.md):

![0042.trapping-rain-water](./assets/problems/42.trapping-rain-water-1.png)

[浏览器中的栈](./thinkings/basic-data-structure.md)：

![basic-data-structure-call-stack](./assets/thinkings/basic-data-structure-call-stack.png)

[backtrack problems](./problems/90.subsets-ii.md):

![backtrack](./assets/problems/backtrack.png)

[0198.house-robber](./problems/198.house-robber.md):

![198.house-robber](./assets/problems/198.house-robber.png)

[0454.4-sum-ii](./problems/454.4-sum-ii.md):

![454.4-sum-ii](./assets/problems/454.4-sum-ii.png)

## Top题目进度

- [Top 100 Liked Questions](https://leetcode.com/problemset/top-100-liked-questions/) (54 / 100)

- [Top Interview Questions](https://leetcode.com/problemset/top-interview-questions/) (82 / 145)
## 传送门

### leetcode 经典题目的解析

> 这里仅列举具有代表性题目，并不是全部题目

#### 简单难度

- [0020.Valid Parentheses](./problems/20.validParentheses.md)
- [0026.remove-duplicates-from-sorted-array](./problems/26.remove-duplicates-from-sorted-array.md)
- [0088.merge-sorted-array](./problems/88.merge-sorted-array.md)
- [0104.maximum-depth-of-binary-tree](./problems/104.maximum-depth-of-binary-tree.md) 🆕
- [0121.best-time-to-buy-and-sell-stock](./problems/121.best-time-to-buy-and-sell-stock.md)
- [0122.best-time-to-buy-and-sell-stock-ii](./problems/122.best-time-to-buy-and-sell-stock-ii.md)
- [0125.valid-palindrome](./problems/125.valid-palindrome.md) 🆕
- [0136.single-number](./problems/136.single-number.md)
- [0155.min-stack](./problems/155.min-stack.md) 🆕
- [0167.two-sum-ii-input-array-is-sorted](./problems/167.two-sum-ii-input-array-is-sorted.md)
- [0172.factorial-trailing-zeroes](./problems/172.factorial-trailing-zeroes.md) 🆕
- [0169.majority-element](./problems/169.majority-element.md)
- [0190.reverse-bits](./problems/190.reverse-bits.md)
- [0191.number-of-1-bits](./problems/191.number-of-1-bits.md)
- [0198.house-robber](./problems/198.house-robber.md)
- [0203.remove-linked-list-elements](./problems/203.remove-linked-list-elements.md)
- [0206.reverse-linked-list](./problems/206.reverse-linked-list.md)
- [0219.contains-duplicate-ii](./problems/219.contains-duplicate-ii.md)
- [0226.invert-binary-tree](./problems/226.invert-binary-tree.md)
- [0263.ugly-number](./problems/263.ugly-number.md)
- [0283.move-zeroes](./problems/283.move-zeroes.md)
- [0342.power-of-four](./problems/342.power-of-four.md)
- [0349.intersection-of-two-arrays](./problems/349.intersection-of-two-arrays.md)
- [0371.sum-of-two-integers](./problems/371.sum-of-two-integers.md)
- [0575.distribute-candies](./problems/575.distribute-candies.md)

#### 中等难度

- [0002. Add Two Numbers](./problems/2.addTwoNumbers.md)
- [0003. Longest Substring Without Repeating Characters](./problems/3.longestSubstringWithoutRepeatingCharacters.md)
- [0005.longest-palindromic-substring](./problems/5.longest-palindromic-substring.md) 🆕
- [0011.container-with-most-water](./problems/11.container-with-most-water.md)
- [0015.3-sum](./problems/15.3-sum.md)
- [0019. Remove Nth Node From End of List](./problems/19.removeNthNodeFromEndofList.md)
- [0024. Swap Nodes In Pairs](./problems/24.swapNodesInPairs.md)
- [0029.divide-two-integers](./problems/29.divide-two-integers.md) 🆕
- [0039.combination-sum](./problems/39.combination-sum.md)
- [0040.combination-sum-ii](./problems/40.combination-sum-ii.md)
- [0046.permutations](./problems/46.permutations.md)
- [0047.permutations-ii](./problems/47.permutations-ii.md)
- [0048.rotate-image](./problems/48.rotate-image.md) 🆕 
- [0049.group-anagrams](./problems/49.group-anagrams.md) 🆕 
- [0055.jump-game](./problems/55.jump-game.md)
- [0056.merge-intervals](./problems/56.merge-intervals.md)
- [0062.unique-paths](./problems/62.unique-paths.md )
- [0073.set-matrix-zeroes](./problems/73.set-matrix-zeroes.md )
- [0075.sort-colors](./problems/75.sort-colors.md)
- [0078.subsets](./problems/78.subsets.md)
- [0086.partition-list](./problems/86.partition-list.md)
- [0090.subsets-ii](./problems/90.subsets-ii.md)
- [0091.decode-ways](./problems/91.decode-ways.md)
- [0092.reverse-linked-list-ii](./problems/92.reverse-linked-list-ii.md)
- [0094.binary-tree-inorder-traversal](./problems/94.binary-tree-inorder-traversal.md)
- [0098.validate-binary-search-tree](./problems/98.validate-binary-search-tree.md) 🆕 
- [0102.binary-tree-level-order-traversal](./problems/102.binary-tree-level-order-traversal.md)
- [0103.binary-tree-zigzag-level-order-traversal](./problems/103.binary-tree-zigzag-level-order-traversal.md)
- [0131.palindrome-partitioning](./problems/131.palindrome-partitioning.md) 🆕 
- [0139.word-break](./problems/139.word-break.md)
- [0144.binary-tree-preorder-traversal](./problems/144.binary-tree-preorder-traversal.md)
- [0150.evaluate-reverse-polish-notation](./problems/150.evaluate-reverse-polish-notation.md)
- [0152.maximum-product-subarray](./problems/152.maximum-product-subarray.md)
- [0199.binary-tree-right-side-view](./problems/199.binary-tree-right-side-view.md)
- [0201.bitwise-and-of-numbers-range](./problems/201.bitwise-and-of-numbers-range.md)
- [0208.implement-trie-prefix-tree](./problems/208.implement-trie-prefix-tree.md)
- [0209.minimum-size-subarray-sum](./problems/209.minimum-size-subarray-sum.md) 
- [0230.kth-smallest-element-in-a-bst](./problems/230.kth-smallest-element-in-a-bst.md)
- [0236.lowest-common-ancestor-of-a-binary-tree](./problems/236.lowest-common-ancestor-of-a-binary-tree.md)🆕 
- [0238.product-of-array-except-self](./problems/238.product-of-array-except-self.md)
- [0240.search-a-2-d-matrix-ii](./problems/240.search-a-2-d-matrix-ii.md)
- [0279.perfect-squares](./problems/279.perfect-squares.md)
- [0309.best-time-to-buy-and-sell-stock-with-cooldown](./problems/309.best-time-to-buy-and-sell-stock-with-cooldown.md) 🆕 
- [0322.coin-change](./problems/322.coin-change.md)
- [0328.odd-even-linked-list](./problems/328.odd-even-linked-list.md)
- [0334.increasing-triplet-subsequence](./problems/334.increasing-triplet-subsequence.md)
- [0365.water-and-jug-problem](./problems/365.water-and-jug-problem.md)
- [0416.partition-equal-subset-sum](./problems/416.partition-equal-subset-sum.md)
- [0445.add-two-numbers-ii](./problems/445.add-two-numbers-ii.md)
- [0454.4-sum-ii](./problems/454.4-sum-ii.md)
- [0494.target-sum](./problems/494.target-sum.md)
- [0516.longest-palindromic-subsequence](./problems/516.longest-palindromic-subsequence.md) 🆕
- [0518.coin-change-2](./problems/518.coin-change-2.md)
- [0609.find-duplicate-file-in-system](./problems/609.find-duplicate-file-in-system.md) 🆕
- [0875.koko-eating-bananas](./problems/875.koko-eating-bananas.md)
- [0877.stone-game](./problems/877.stone-game.md)
- [0887.super-egg-drop](./problems/887.super-egg-drop.md)
- [0900.rle-iterator](./problems/900.rle-iterator.md)

#### 困难难度
- [0023.merge-k-sorted-lists](./problems/23.merge-k-sorted-lists.md)
- [0032.longest-valid-parentheses](./problems/32.longest-valid-parentheses.md) 🆕
- [0042.trapping-rain-water](./problems/42.trapping-rain-water.md)
- [0128.longest-consecutive-sequence](./problems/128.longest-consecutive-sequence.md) 🆕
- [0145.binary-tree-postorder-traversal](./problems/145.binary-tree-postorder-traversal.md)
- [0146.lru-cache](./problems/146.lru-cache.md)
- [0239.sliding-window-maximum](./problems/239.sliding-window-maximum.md)
- [0295.find-median-from-data-stream](./problems/295.find-median-from-data-stream.md) 🆕
- [0301.remove-invalid-parentheses](./problems/301.remove-invalid-parentheses.md)

### 数据结构与算法的总结

- [数据结构](./thinkings/basic-data-structure.md)（草稿）
- [基础算法](./thinkings/basic-algorithm.md)（草稿）
- [二叉树的遍历](./thinkings/binary-tree-traversal.md)
- [动态规划](./thinkings/dynamic-programming.md)
- [哈夫曼编码和游程编码](./thinkings/run-length-encode-and-huffman-encode.md)
- [布隆过滤器](./thinkings/bloom-filter.md)
- [字符串问题](./thinkings/string-problems.md)

### anki 卡片

Anki主要分为两个部分:一部分是关键点到题目的映射，另一部分是题目到思路，关键点，代码的映射。

全部卡片都在[anki-card](./assets/anki/leetcode.apkg)

使用方法：

anki - 文件 - 导入 - 下拉格式选择“打包的 anki集合”，然后选中你下载好的文件，确定即可。

更多关于anki使用方法的请查看[anki官网](https://apps.ankiweb.net/)

目前已更新卡片一览（仅列举正面）：

- 二分法解决问题的关键点是什么，相关问题有哪些?
- 如何用栈的特点来简化操作， 涉及到的题目有哪些？
- 双指针问题的思路以及相关题目有哪些？
- 滑动窗口问题的思路以及相关题目有哪些？
- 回溯法解题的思路以及相关题目有哪些？
- 数论解决问题的关键点是什么，相关问题有哪些?
- 位运算解决问题的关键点是什么，相关问题有哪些?

> 已加入的题目有：#2 #3 #11

### 计划

- [anki 卡片 完善](./assets/anki/)

- [字符串类问题汇总](./todo/str/)

## 交流群

现在还是初级阶段，需要大家的意见和反馈，为了减少沟通成本，我组建了交流群。大家可以扫码进入

### QQ 群

![qq-group-chat](./assets/qq-group-chat.png)

### 微信群

![wechat-group-chat](./assets/wechat-group-chat.jpeg)

(由于微信的限制，100个人以上只能邀请加入， 你可以添加我的机器人回复“leetcode”拉你进群)

### Telegram

http://t.me/leetcode_intl

## 贡献

- 如果有想法和创意，请提[issue](https://github.com/azl397985856/leetcode/issues)或者进群提
- 如果想贡献代码，请提[PR](https://github.com/azl397985856/leetcode/pulls)
- 如果需要修改项目中图片，[这里](./assets/drawio/)存放了项目中绘制图的源代码， 大家可以用[draw.io](https://www.draw.io/)打开进行编辑。

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