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Data Structure & Algorithm Problems' Solutions

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> since 2019-11-01 15:50

## Introduction
Data Structure &amp; Algorithm Problems' Solutions for interview, implemented in Java, C, Python, Go.

Mind Map: https://www.processon.com/view/link/5f9193b81e085307a09e598b

Data Structure implemented in Java: https://github.com/FreetechRevise/data-structure

## LeetCode (376)

| Tags | | | |
| ------------------- | ---------------- | ------------------- | ------------------ |
| Binary Search | Math | Two Pointers | String |
| Array | Hash Table | Linked List | Divide and Conquer |
| Sort | Bit Manipulation | Tree | DFS |
| Design | Trie | Queue | BFS |
| Graph | Heap | Dynamic Programming | Backtracking |
| Greedy | Line Sweep | Stack | Union Find |
| Binary Indexed Tree | Segment Tree | Minimax | Brainteaser |
| Geometry | Sliding Window | Topological Sort | Memoization |
| Concurrency | Quick Select | Prefix Sum | Database |

| No. | Title | Desc | Complexity | Solution | Difficulty | Tags |
| ---- | ------------------------------------------------------------ | ---------------------------------- | ------------------------------------------------------------ | ---------- | -------------------------------------------------------- | -------------------------------------------------------- |
| 1 | [Two Sum](https://leetcode.com/problems/two-sum) | 两数之和 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1.java) [Python](python/src/problem/leetcode/easy/leetcode_1.py) [C](c/easy/leetcode_1.c) [Go](go/src/problem/leetcode1.go) | Easy | Array Hash Table Two Pointers |
| 2 | [Add Two Numbers](https://leetcode.com/problems/add-two-numbers) | 两数相加 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode2.java) [Python](python/src/problem/leetcode/medium/leetcode_2.py) [C](c/medium/leetcode_2.c) [Go](go/src/problem/leetcode2.go) | Medium | Linked List Math |
| 3 | [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters) | 无重复字符的最长子串 | Time: O(n) Space: O(m) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode3.java) [Python](python/src/problem/leetcode/medium/leetcode_3.py) [C](c/medium/leetcode_3.c) [Go](go/src/problem/leetcode3.go) | Medium | Hash Table Two Pointers String Sliding Window |
| 4 | [Median of Two Sorted Arrays](https://leetcode.com/problems/median-of-two-sorted-arrays) | 求两个有序数组的中位数 | Time: O(log(k)) <= O(log(m+n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode4.java) [Python](python/src/problem/leetcode/hard/leetcode_4.py) [C](c/hard/leetcode_4.c) | Hard | Array Binary Search Divide and Conquer |
| 5 | [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring) | 最长回文子串 | Time: O(n^2) Space: O(n^2) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode5.java) [Python](python/src/problem/leetcode/medium/leetcode_5.py) [C](c/medium/leetcode_5.c) [Go](go/src/problem/leetcode5.go) | Medium | String Dynamic Programming Two Pointers |
| 6 | [Zigzag Conversion](https://leetcode.com/problems/zigzag-conversion) | Z 字形变换 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode6.java) [C](c/medium/leetcode_6.c) | Medium | String |
| 7 | [Reverse Integer](https://leetcode.com/problems/reverse-integer) | 整数反转 | Time: O(k) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode7.java) [Python](python/src/problem/leetcode/easy/leetcode_7.py) [C](c/easy/leetcode_7.c) [Go](go/src/problem/leetcode7/reverse.go) | Easy | Math |
| 8 | [String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi) | 字符串转整数 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode8.java) [C](c/medium/leetcode_8.c) | Medium | Math String |
| 9 | [Palindrome Number](https://leetcode.com/problems/palindrome-number) | 回文数字 | Time: O(m) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode9.java) [Python](python/src/problem/leetcode/easy/leetcode_9.py) [C](c/easy/leetcode_9.c) [Go](go/src/problem/leetcode9/isPalindrome.go) | Easy | Math Two Pointers |
| 10 | [Regular Expression Matching](https://leetcode.com/problems/regular-expression-matching) | 正则表达式匹配 | Time: O(m\*n) Space: O(m\*n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode10.java) [Go](go/src/problem/leetcode10/isMatch.go) | Hard | String Backtracking Dynamic Programming |
| 11 | [Container With Most Water](https://leetcode.com/problems/container-with-most-water) | 盛最多水的容器 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode11.java) [Python](python/src/problem/leetcode/medium/leetcode_11.py) [C](c/easy/leetcode_11.c) [Go](go/src/problem/leetcode11.go) | Medium | Array Two Pointers |
| 12 | [Integer to Roman](https://leetcode.com/problems/integer-to-roman) | 整数转罗马数字 | Time: O(1) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode12.java) | Medium | Math String |
| 13 | [Roman to Integer](https://leetcode.com/problems/roman-to-integer) | 罗马数字转整数 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode13.java) [Python](python/src/problem/leetcode/easy/leetcode_13.py) [C](c/easy/leetcode_13.c) | Easy | Math String |
| 14 | [Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix) | 最长公共前缀 | Time: O(k\*n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode14.java) [Python](python/src/problem/leetcode/easy/leetcode_14.py) [C](c/easy/leetcode_14.c) | Easy | String |
| 15 | [3Sum](https://leetcode.com/problems/3sum) | 三数之和 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode15.java) [Python](python/src/problem/leetcode/medium/leetcode_15.py) [C](c/medium/leetcode_15.c) | Medium | Array Two Pointers |
| 16 | [3Sum Closest](https://leetcode.com/problems/3sum-closest) | 求和最接近目标值的三个数 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode16.java) [Python](python/src/problem/leetcode/medium/leetcode_16.py) [C](c/medium/leetcode_16.c) | Medium | Array Two Pointers |
| 17 | [Letter Combinations of a Phone Number](https://leetcode.com/problems/letter-combinations-of-a-phone-number) | 电话号码的字母组合 | Time: O(4^n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode17.java) [Python](python/src/problem/leetcode/medium/leetcode_17.py) [C](c/medium/leetcode_17.c) | Medium | String Backtracking |
| 18 | [4Sum](https://leetcode.com/problems/4sum) | 四数之和 | Time: O(n^3) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode18.java) [Python](python/src/problem/leetcode/medium/leetcode_18.py) [C](c/medium/leetcode_18.c) | Medium | Two Pointers Array |
| 19 | [Remove Nth Node From End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list) | 删除链表的倒数第 N 个节点 | Time: O(k) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode19.java) [Python](python/src/problem/leetcode/medium/leetcode_19.py) [C](c/medium/leetcode_19.c) [Go](go/src/problem/leetcode19/removeNthFromEnd.go) | Medium | Linked List Two Pointers |
| 20 | [Valid Parentheses](https://leetcode.com/problems/valid-parentheses) | 有效的括号 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode20.java) [Python](python/src/problem/leetcode/easy/leetcode_20.py) [C](c/easy/leetcode_20.c) [Go](go/src/problem/leetcode20/isValid.go) | Easy | String Stack |
| 21 | [Merge Two Sorted Lists](https://leetcode.com/problems/merge-two-sorted-lists) | 合并两个有序链表 | Time: O(m+n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode21.java) [Python](python/src/problem/leetcode/easy/leetcode_21.py) [C](c/easy/leetcode_21.c) | Easy | Linked List |
| 22 | [Generate Parentheses](https://leetcode.com/problems/generate-parentheses) | 括号生成 | Time: O(4^n / sqrt(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode22.java) [Python](python/src/problem/leetcode/medium/leetcode_22.py) [C](c/medium/leetcode_22.c) [Go](go/src/problem/leetcode22/generateParenthesis.go) | Medium | String Backtracking |
| 23 | [Merge k Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists) | 合并 K 个升序链表 | Time: O(k\*n\*log(k)) Space: O(k) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode23.java) [C](c/hard/leetcode_23.c) | Hard | Linked List Divide and Conquer Heap |
| 24 | [Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs) | 两两交换链表中的节点 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode24.java) [Python](python/src/problem/leetcode/medium/leetcode_24.py) [C](c/medium/leetcode_24.c) [Go](go/src/problem/leetcode24/swapPairs.go) | Medium | Linked List |
| 25 | [Reverse Nodes In K Group](https://leetcode.com/problems/reverse-nodes-in-k-group) | K 个一组翻转链表 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode25.java) [Go](go/src/problem/leetcode25.go) | Hard | Linked List |
| 26 | [Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array) | 删除排序数组中的重复项 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode26.java) [Python](python/src/problem/leetcode/easy/leetcode_26.py) | Easy | Two Pointers Array |
| 27 | [Remove Element](https://leetcode.com/problems/remove-element) | 移除数组中指定数字 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode27.java) [Python](python/src/problem/leetcode/easy/leetcode_27.py) | Easy | Two Pointers Array |
| 28 | [Implement strStr()](https://leetcode.com/problems/implement-strstr) | 实现 strstr | Time: O((n-m+1)\*m) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode28.java) [Python](python/src/problem/leetcode/easy/leetcode_28.py) | Easy | Two Pointers String |
| 29 | [Divide Two Integers](https://leetcode.com/problems/divide-two-integers) | 两数相除 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode29.java) | Medium | Math Binary Search |
| 31 | [Next Permutation](https://leetcode.com/problems/next-permutation) | 下一个排列 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode31.java) [Python](python/src/problem/leetcode/medium/leetcode_31.py) | Medium | Array Two Pointers |
| 32 | [Longest Valid Parentheses](https://leetcode.com/problems/longest-valid-parentheses) | 有效括号的最大长度 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode32.java) [Go](go/src/problem/leetcode32/longestValidParentheses.go) | Hard | String Dynamic Programming Stack |
| 33 | [Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array) | 搜索旋转排序数组 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode33.java) [Python](python/src/problem/leetcode/medium/leetcode_33.py) | Medium | Array Binary Search |
| 34 | [Find First and Last Position of Element in Sorted Array](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array) | 在排序数组中查找元素的第一个和最后一个位置 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode34.java) [Python](python/src/problem/leetcode/medium/leetcode_34.py) | Medium | Array Binary Search |
| 35 | [Search Insert Position](https://leetcode.com/problems/search-insert-position) | 搜索插入位置 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode35.java) [Python](python/src/problem/leetcode/easy/leetcode_35.py) | Medium | Binary Search |
| 36 | [Valid Sudoku](https://leetcode.com/problems/valid-sudoku) | 判断数独的有效性 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode36.java) [Python](python/src/problem/leetcode/medium/leetcode_36.py) | Medium | Hash Table |
| 38 | [Count and Say](https://leetcode.com/problems/count-and-say) | 外观数列 | Time: O(1.3^n) Space: O(1.3^n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode38.java) [Python](python/src/problem/leetcode/easy/leetcode_38.py) | Easy | String |
| 39 | [Combination Sum](https://leetcode.com/problems/combination-sum) | 组合总和 | Time: O(n^(target/min)) Space: O(target/min) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode39.java) [Python](python/src/problem/leetcode/medium/leetcode_39.py) | Medium | Array Backtracking |
| 40 | [Combination Sum II](https://leetcode.com/problems/combination-sum-ii) | 组合总和 II | Time: O(n^(target/min)) Space: O(target/min) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode40.java) | Medium | Array Backtracking |
| 41 | [First Missing Positive](https://leetcode.com/problems/first-missing-positive) | 缺失的第一个正数 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode41.java) [Go](go/src/problem/leetcode41/firstMissingPositive.go) | Hard | Array Hash Table |
| 42 | [Trapping Rain Water](https://leetcode.com/problems/trapping-rain-water) | 接雨水 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode42.java) [Go](go/src/problem/leetcode42.go) | Hard | Array Two Pointers Stack |
| 44 | [Wildcard Matching](https://leetcode.com/problems/wildcard-matching) | 通配符匹配 | Time: O(m\*n) Space: O(m\*n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode44.java) | Hard | Dynamic Programming |
| 43 | [Submissions](https://leetcode.com/problems/multiply-strings/submissions) | 字符串相乘 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode43.java) | Medium | Math String |
| 45 | [Jump Game II](https://leetcode.com/problems/jump-game-ii) | 跳跃游戏 II | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode45.java) [Go](go/src/problem/leetcode45/jump.go) | Hard | Array Greedy |
| 46 | [Permutations](https://leetcode.com/problems/permutations) | 全排列 | Time: O(n\*n!) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode46.java) [Python](python/src/problem/leetcode/medium/leetcode_46.py) | Medium | Backtracking |
| 47 | [Permutations II](https://leetcode.com/problems/permutations-ii) | 全排列 II | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode47.java) [Python](python/src/problem/leetcode/medium/leetcode_47.py) | Medium | Hash Table Backtracking |
| 48 | [Rotate Image](https://leetcode.com/problems/rotate-image) | 旋转图像 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode48.java) [Python](python/src/problem/leetcode/medium/leetcode_48.py) | Medium | Array |
| 49 | [Group Anagrams](https://leetcode.com/problems/anagrams) | 变位词分组 | Time: O(n*k) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode49.java) | Medium | Hash Table String |
| 50 | [Pow(x, n)](https://leetcode.com/problems/powx-n) | Pow(x, n) | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode50.java) | Medium | Math |
| 51 | [N Queens](https://leetcode.com/problems/n-queens) | N 皇后 | Time: O(n!) Space: O(n^2) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode51.java) | Hard | Backtracking |
| 52 | [N Queens II](https://leetcode.com/problems/n-queens-ii) | N 皇后 II | Time: O(n!) Space: O(n^2) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode52.java) | Hard | Backtracking |
| 53 | [Maximum Subarray](https://leetcode.com/problems/maximum-subarray) | 最大子序和 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode53.java) [Python](python/src/problem/leetcode/easy/leetcode_53.py) [Go](go/src/problem/leetcode53/maxSubArray.go) | Easy | Dynamic Programming Divide and Conquer Array |
| 54 | [Spiral Matrix](https://leetcode.com/problems/spiral-matrix) | 螺旋矩阵 | Time: O(m\*n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode54.java) [Python](python/src/problem/leetcode/medium/leetcode_54.py) [Go](go/src/problem/leetcode54/spiralOrder.go) | Medium | Array |
| 55 | [Jump Game](https://leetcode.com/problems/jump-game) | 跳跃游戏 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode55.java) [Python](python/src/problem/leetcode/medium/leetcode_55.py) | Medium | Array Greedy |
| 56 | [Merge Intervals](https://leetcode.com/problems/merge-intervals) | 合并区间 | Time: O(n\*log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode56.java) | Medium | Array Sort |
| 58 | [Length of Last Word](https://leetcode.com/problems/length-of-last-word) | 最后一个单词的长度 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode58.java) [Python](python/src/problem/leetcode/easy/leetcode_58.py) | Easy | String |
| 59 | [Spiral Matrix II](https://leetcode.com/problems/spiral-matrix-ii) | 输出旋转矩阵 | Time: O(m*n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode59.java) | Medium | Array |
| 61 | [Rotate List](https://leetcode.com/problems/rotate-list) | 旋转链表 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode61.java) [Python](python/src/problem/leetcode/medium/leetcode_61.py) | Medium | Linked List |
| 62 | [Unique Paths](https://leetcode.com/problems/unique-paths) | 不同路径 | Time: O(min(m, n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode62.java) [Python](python/src/problem/leetcode/medium/leetcode_62.py) | Medium | Array Dynamic Programming |
| 63 | [Unique Paths II](https://leetcode.com/problems/unique-paths-ii) | 不同路径 II | Time: O(m\*n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode63.java) [Python](python/src/problem/leetcode/medium/leetcode_63.py) | Medium | Array Dynamic Programming |
| 64 | [Minimum Path Sum](https://leetcode.com/problems/minimum-path-sum) | 最小路径和 | Time: O(m\*n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode64.java) | Medium | Array Dynamic Programming |
| 66 | [Plus One](https://leetcode.com/problems/plus-one) | 加一 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode66.java) [Python](python/src/problem/leetcode/easy/leetcode_66.py) | Easy | Array |
| 67 | [Add Binary](https://leetcode.com/problems/add-binary) | 二进制求和 | Time: O(max(m, n)) Space: O(max(m, n)) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode67.java) [Python](python/src/problem/leetcode/easy/leetcode_67.py) | Easy | Math String |
| 69 | [Sqrt(x)](https://leetcode.com/problems/sqrtx) | 实现平方根函数 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode69.java) [Go](go/src/problem/leetcode69/mySqrt.go) | Easy | Math Binary Search |
| 70 | [Climbing Stairs](https://leetcode.com/problems/climbing-stairs) | 爬楼梯 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode70.java) [Python](python/src/problem/leetcode/easy/leetcode_70.py) [Go](go/src/problem/leetcode70/climbStairs.go) | Easy | Dynamic Programming |
| 71 | [Simplify Path](https://leetcode.com/problems/simplify-path) | 简化路径 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode71.java) | Medium | Stack String |
| 72 | [Edit Distance](https://leetcode.com/problems/edit-distance) | 编辑距离 | Time: O(m\*n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode72.java) [Go](go/src/problem/leetcode72/minDistance.go) | Hard | String Dynamic Programming |
| 73 | [Set Matrix Zeroes](https://leetcode.com/problems/set-matrix-zeroes) | 矩阵置零 | Time: O(m\*n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode73.java) | Medium | Array |
| 74 | [Search a 2D Matrix](https://leetcode.com/problems/search-a-2d-matrix) | 搜索二维矩阵 | Time: O(log(m\*n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode74.java) | Medium | Array Binary Search |
| 75 | [Sort Colors](https://leetcode.com/problems/sort-colors) | 颜色分类 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode75.java) | Medium | Array Two Pointers Sort |
| 76 | [Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring) | 最小覆盖子串 | Time: O(n) Space: O(m) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode76.java) | Hard | Hash Table Two Pointers String |
| 77 | [Combinations](https://leetcode.com/problems/combinations) | 组合 | Time: O(k\*C(n, k)) Space: O(k\*C(n, k)) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode77.java) [Python](python/src/problem/leetcode/medium/leetcode_77.py) | Medium | Backtracking |
| 78 | [Subsets](https://leetcode.com/problems/subsets) | 子集 | Time: O(2^n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode78.java) | Medium | Array Backtracking Bit Manipulation |
| 79 | [Word Search](https://leetcode.com/problems/word-search) | 搜索单词 | Time: O(m\*n\*3^k) Space: O(m*n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode79.java) [Go](go/src/problem/leetcode79/exist.go) | Medium | Array Backtracking DFS |
| 80 | [Remove Duplicates From Sorted Array II](https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii) | 删除排序数组中的重复项 II | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode80.java) | Medium | Array Two Pointers |
| 81 | [Search In Rotated Sorted Array II](https://leetcode.com/problems/search-in-rotated-sorted-array-ii) | 搜索旋转排序数组 II | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode81.java) | Medium | Array Binary Search |
| 82 | [Remove Duplicates from Sorted List II](https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii) | 删除排序链表中的重复元素 II | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode82.java) | Medium | Linked List |
| 83 | [Remove Duplicates from Sorted List](https://leetcode.com/problems/remove-duplicates-from-sorted-list) | 删除排序链表中的重复元素 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode83.java) [Python](python/src/problem/leetcode/easy/leetcode_83.py) | Easy | Linked List |
| 84 | [Largest Rectangle in Histogram](https://leetcode.com/problems/largest-rectangle-in-histogram) | 直方图中的最大矩形 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode84.java) [Go](go/src/problem/leetcode84/largestRectangleArea.go) | Hard | Array Stack |
| 85 | [Maximal Rectangle](https://leetcode.com/problems/maximal-rectangle) | 最大矩形 | Time: O(m\*n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode85.java) | Hard | Array Stack |
| 86 | [Partition List](https://leetcode.com/problems/partition-list) | 分隔链表 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode86.java) | Medium | Linked List Two Pointers |
| 88 | [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array) | 合并两个有序数组 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode88.java) [Python](python/src/problem/leetcode/easy/leetcode_88.py) | Easy | Two Pointers Array |
| 90 | [Subsets II](https://leetcode.com/problems/subsets-ii) | 子集 II | Time: O(2^n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode90.java) | Medium | Array Backtracking |
| 91 | [Decode Ways](https://leetcode.com/problems/decode-ways) | 解码方式 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode91.java) [Go](go/src/problem/leetcode91/numDecodings.go) | Medium | String Dynamic Programming |
| 92 | [Reverse Linked List II](https://leetcode.com/problems/reverse-linked-list-ii) | 反转链表 II | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode92.java) | Medium | Linked List |
| 93 | [Restore IP Addresses](https://leetcode.com/problems/restore-ip-addresses) | 复原 IP 地址 | Time: O(n^4) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode93.java) | Medium | String Backtracking |
| 94 | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal) | 二叉树的中序遍历 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode94.java) | Medium | Hash Table Stack Tree |
| 95 | [Unique Binary Search Trees II](https://leetcode.com/problems/unique-binary-search-trees-ii) | 用 1~n 生成二叉搜索树 | Time: O(4^n / n^(3/2)) Space: O(4^n / n^(3/2)) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode95.java) [Python](python/src/problem/leetcode/easy/leetcode_100.py) | Medium | Dynamic Programming Tree |
| 96 | [Unique Binary Search Trees](https://leetcode.com/problems/unique-binary-search-trees) | 不同的二叉搜索树 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode96.java) | Medium | Dynamic Programming Tree Math |
| 97 | [Interleaving String](https://leetcode.com/problems/interleaving-string) | 交错字符串 | Time: O(m\*n) Space: O(m\*n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode97.java) | Hard | Dynamic Programming Backtracking |
| 98 | [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree) | 检验二叉搜索树 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode98.java) [Go](go/src/problem/leetcode98/isValidBST.go) | Medium | Tree DFS |
| 99 | [Recover Binary Search Tree](https://leetcode.com/problems/recover-binary-search-tree/submissions) | 恢复搜索二叉树 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode99.java) | Hard | Tree DFS |
| 100 | [Same Tree](https://leetcode.com/problems/same-tree) | 相同的树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode100.java) [Python](python/src/problem/leetcode/easy/leetcode_100.py) | Easy | Tree Stack |
| 101 | [Symmetric Tree](https://leetcode.com/problems/symmetric-tree) | 对称二叉树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode101.java) [Python](python/src/problem/leetcode/easy/leetcode_101.py) | Easy | Tree DFS BFS |
| 102 | [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal) | 二叉树的层序遍历 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode102.java) [Python](python/src/problem/leetcode/easy/leetcode_102.py) [Go](go/src/problem/leetcode102/levelOrder.go) | Easy | Tree BFS |
| 103 | [Binary Tree Zigzag Level Order Traversal](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal) | 二叉树的锯齿形层序遍历 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode103.java) | Medium | Tree BFS Queue |
| 104 | [Maximum Depth of Binary Tree](https://leetcode.com/problems/maximum-depth-of-binary-tree) | 二叉树的最大深度 | Time: O(n) Space: (n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode104.java) [Python](python/src/problem/leetcode/easy/leetcode_104.py) | Easy | Tree DFS |
| 105 | [Construct Binary Tree from Preorder and Inorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal) | 从前序与中序遍历序列构造二叉树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode105.java) [Go](go/src/problem/leetcode105/buildTree.go) | Medium | Array Tree DFS |
| 106 | [Construct Binary Tree from Inorder and Postorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal) | 从中序与后序遍历序列构造二叉树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode106.java) | Medium | Array Tree DFS |
| 107 | [Binary Tree Level Order Traversal II](https://leetcode.com/problems/binary-tree-level-order-traversal-ii) | 二叉树的层序遍历 II | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1.java) [Python](python/src/problem/leetcode/easy/leetcode_107.py) | Easy | Array Hash Table Two Pointers |
| 108 | [Convert Sorted Array to Binary Search Tree](https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree) | 将有序数组转换为二叉搜索树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode108.java) [Python](python/src/problem/leetcode/easy/leetcode_108.py) | Easy | Tree DFS |
| 109 | [Convert Sorted List to Binary Search Tree](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree) | 有序链表转换二叉搜索树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode109.java) | Medium | Linked List DFS |
| 110 | [Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree) | 平衡二叉树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode110.java) [Python](python/src/problem/leetcode/easy/leetcode_110.py) | Easy | Tree DFS |
| 111 | [Minimum Depth of Binary Tree](https://leetcode.com/problems/minimum-depth-of-binary-tree) | 二叉树的最小深度 | Time: O(n) Space: (n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode111.java) [Python](python/src/problem/leetcode/easy/leetcode_111.py) [Go](go/src/problem/leetcode101/isSymmetric.go) | Easy | Tree DFS BFS |
| 112 | [Path Sum](https://leetcode.com/problems/path-sum) | 路径总和 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode112.java) [Python](python/src/problem/leetcode/easy/leetcode_112.py) [Go](go/src/problem/leetcode112/hasPathSum.go) | Easy | Tree DFS |
| 113 | [Path Sum II](https://leetcode.com/problems/path-sum-ii) | 路径总和 II | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode113.java) | Medium | Tree DFS Backtracking |
| 114 | [Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list) | 二叉树展开为链表 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode114.java) | Medium | Tree DFS |
| 116 | [Populating Next Right Pointers in Each Node](https://leetcode.com/problems/populating-next-right-pointers-in-each-node) | 填充每个节点的下一个右侧节点指针 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode116.java) | Medium | Tree DFS BFS |
| 118 | [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle) | 杨辉三角 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode118.java) [Python](python/src/problem/leetcode/easy/leetcode_118.py) | Easy | Array |
| 119 | [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii) | 杨辉三角 2 | Time: O(k^2) Space: O(k^2) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode119.java) [Python](python/src/problem/leetcode/easy/leetcode_119.py) | Easy | Array Math |
| 120 | [Triangle](https://leetcode.com/problems/triangle) | 三角形最小路径和 | Time: O(n^2) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode120.java) [Python](python/src/problem/leetcode/medium/leetcode_120.py) | Medium | Array Dynamic Programming |
| 121 | [Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock) | 买卖股票的最佳时机 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode121.java) [Go](go/src/problem/leetcode121/maxProfit.go) | Medium | Array Dynamic Programming |
| 122 | [Best Time to Buy and Sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii) | 买卖股票的最佳时机 II | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode122.java) [Python](python/src/problem/leetcode/easy/leetcode_122.py) | Easy | Array Greedy |
| 123 | [Best Time to Buy and Sell Stock III](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii) | 买卖股票的最佳时机 III | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode123.java) | Hard | Dynamic Programming Array |
| 124 | [Binary Tree Maximum Path Sum](https://leetcode.com/problems/binary-tree-maximum-path-sum) | 二叉树中的最大路径和 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode124.java) | Hard | Tree DFS |
| 125 | [Valid Palindrome](https://leetcode.com/problems/valid-palindrome) | 验证回文串 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode125.java) [Python](python/src/problem/leetcode/easy/leetcode_125.py) | Easy | Two Pointers String |
| 128 | [Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence) | 最长连续序列 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode128.java) | Hard | Sort Hash Table |
| 129 | [Sum Root to Leaf Numbers](https://leetcode-cn.com/problems/sum-root-to-leaf-numbers) | 求根节点到叶节点数字之和 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode129.java) | Medium | Tree BFS DFS |
| 130 | [Surrounded Regions](https://leetcode.com/problems/surrounded-regions) | 被围绕的区域 | Time: O(m\*n) Space: O(m\*n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode130.java) | Medium | DFS BFS Union Find |
| 131 | [Palindrome Partitioning](https://leetcode.com/problems/palindrome-partitioning) | 分割回文串 | Time: O(2^n) Space: O(n^2) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode131.java) | Medium | Backtracking Dynamic Programming DFS |
| 132 | [Palindrome Partitioning II](https://leetcode.com/problems/palindrome-partitioning-ii) | 分割回文串 II | Time: O(n^2) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode132.java) [Go](go/src/problem/leetcode132/minCut.go) | Hard | Dynamic Programming |
| 133 | [Clone Graph](https://leetcode.com/problems/clone-graph) | 图的深拷贝 | Time: O(E) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode133.java) | Medium | Graph DFS BFS |
| 134 | [Gas Station](https://leetcode.com/problems/gas-station) | 加油站 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode134.java) [Go](go/src/problem/leetcode134/canCompleteCircuit.go) | Medium | Greedy |
| 135 | [Candy](https://leetcode.com/problems/candy) | 分发糖果 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode135.java) [Go](go/src/problem/leetcode135/candy.go) | Hard | Greedy |
| 136 | [Single Number](https://leetcode.com/problems/single-number) | 只出现一次的数字 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode136.java) | Medium | Hash Table Bit Manipulation |
| 138 | [Copy List with Random Pointer](https://leetcode.com/problems/copy-list-with-random-pointer) | 含随机指针的链表拷贝 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode138.java) | Medium | Linked List Hash Table |
| 139 | [Word Break](https://leetcode.com/problems/word-break) | 单词拆分 | Time: O(n^2) Space: O(n+m) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode139.java) | Medium | Dynamic Programming |
| 140 | [Word Break II](https://leetcode.com/problems/word-break-ii) | 单词拆分 II | Time: O(n^2) Space: O(n+m) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode140.java) | Hard | Dynamic Programming Backtracking |
| 141 | [Linked List Cycle](https://leetcode.com/problems/linked-list-cycle) | 环形链表 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode141.java) | Medium | Linked List Two Pointers |
| 142 | [Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii) | 环形链表 II | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode142.java) | Medium | Linked List Two Pointers |
| 143 | [Reorder List](https://leetcode.com/problems/reorder-list) | 重排链表 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode143.java) | Medium | Linked List Two Pointers |
| 144 | [Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal) | 二叉树的前序遍历 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode144.java) | Medium | Stack Tree |
| 145 | [Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal) | 二叉树的后序遍历 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode145.java) | Medium | Stack Tree |
| 146 | [LRU Cache](https://leetcode.com/problems/lru-cache) | LRU 缓存机制 | Time: O(1) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode146.java) [Go](go/src/problem/leetcode146/lru.go) | Medium | Design Hash Table Linked List |
| 147 | [Insertion Sort List](https://leetcode.com/problems/insertion-sort-list) | 单链表插入排序 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode147.java) | Medium | Linked List Sort |
| 148 | [Sort List](https://leetcode.com/problems/sort-list) | 排序链表 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode148.java) [Go](go/src/problem/leetcode148/sortList.go) | Medium | Linked List Sort |
| 151 | [Reverse Words in a String](https://leetcode.com/problems/reverse-words-in-a-string) | 翻转字符串里的单词 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode151.java) | Medium | String |
| 152 | [Maximum Product Subarray](https://leetcode.com/problems/maximum-product-subarray) | 乘积最大子数组 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode152.java) | Medium | Array Dynamic Programming |
| 153 | [Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array) | 寻找旋转排序数组中的最小值 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode153.java) | Medium | Array Binary Search |
| 154 | [Find Minimum in Rotated Sorted Array II](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii) | 寻找旋转排序数组中的最小值 II | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode154.java) | Hard | Array Binary Search |
| 155 | [Min Stack](https://leetcode.com/problems/min-stack) | 最小栈 | Time: O(1) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode155.java) [Python](python/src/problem/leetcode/easy/leetcode_155.py) | Easy | Stack Design |
| 160 | [Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists) | 相交链表 | Time: O(m+n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode160.java) [Python](python/src/problem/leetcode/easy/leetcode_160.py) [Go](go/src/problem/leetcode160/getIntersectionNode.go) | Easy | Linked List |
| 162 | [Find Peak Element](https://leetcode.com/problems/find-peak-element) | 寻找峰值 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode162.java) | Medium | Array Binary Search |
| 165 | [Compare Version Numbers](https://leetcode.com/problems/compare-version-numbers) | 比较版本号 | Time: O(m+n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode165.java) | Medium | Two Pointers String |
| 167 | [Two Sum II - Input array is sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted) | 两数之和 II - 输入有序数组 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode167.java) | Medium | Two Pointers Array Binary Search |
| 168 | [Excel Sheet Column Title](https://leetcode.com/problems/excel-sheet-column-title) | Excel 表格的列标题 | Time: O(log26(n)) Space: O(log26(n)) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode168.java) [Python](python/src/problem/leetcode/easy/leetcode_168.py) | Easy | Math |
| 169 | [Majority Element](https://leetcode.com/problems/majority-element) | 多数元素 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode169.java) [Python](python/src/problem/leetcode/easy/leetcode_169.py) | Easy | Array Divide and Conquer Bit Manipulation |
| 170 | [Two Sum III - Data structure design](https://leetcode.com/problems/two-sum-iii-data-structure-design) | 设计一个类求和为给定值的两个数 | Time: O(n) (add), O(1) (find) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode170.java) [Python](python/src/problem/leetcode/easy/leetcode_170.py) | Easy | Design Hash Table |
| 171 | [Excel Sheet Column Number](https://leetcode.com/problems/excel-sheet-column-number) | Excel 表格的列编号 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode171.java) [Python](python/src/problem/leetcode/easy/leetcode_171.py) | Easy | Math |
| 172 | [Factorial Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes) | 阶乘末尾 0 的个数 | Time: O(log5(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode172.java) [Python](python/src/problem/leetcode/easy/leetcode_172.py) | Easy | Math |
| 173 | [Binary Search Tree Iterator](https://leetcode.com/problems/binary-search-tree-iterator) | 二叉搜索树迭代器 | Time(avg): O(1) Space(avg): O(h) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode173.java) | Medium | Tree Stack Design |
| 179 | [Largest Number](https://leetcode.com/problems/largest-number/submissions) | 最大数 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode179.java) [Python](python/src/problem/leetcode/medium/leetcode_179.py) | Medium | Sort |
| 188 | [Best Time to Buy and Sell Stock IV](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv) | 买卖股票的最佳时机 IV | Time: O(n^2) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode188.java) | Hard | Dynamic Programming |
| 189 | [Rotate Array](https://leetcode.com/problems/rotate-array) | 旋转数组 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode189.java) [Python](python/src/problem/leetcode/easy/leetcode_189.py) | Easy | Array |
| 190 | [Reverse Bits](https://leetcode.com/problems/reverse-bits) | 翻转整数的二进制位 | Time: O(1) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode190.java) [Python](python/src/problem/leetcode/easy/leetcode_190.py) | Easy | Bit Manipulation |
| 191 | [Number of 1 Bits](https://leetcode.com/problems/number-of-1-bits) | 二进制中 1 的个数 | Time: O(m) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode191.java) [Python](python/src/problem/leetcode/easy/leetcode_191.py) | Easy | Bit Manipulation |
| 198 | [House Robber](https://leetcode.com/problems/house-robber) | 打家劫舍 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode198.java) [Python](python/src/problem/leetcode/easy/leetcode_198.py) [Go](go/src/problem/leetcode198/rob.go) | Easy | Dynamic Programming |
| 199 | [Binary Tree Right Side View](https://leetcode.com/problems/binabinary-tree-right-side-viewry-tree-right-side-view/submissions) | 二叉树的右视图 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode199.java) [Python](python/src/problem/leetcode/medium/leetcode_199.py) | Medium | Tree BFS DFS |
| 200 | [Number of Islands](https://leetcode.com/problems/number-of-islands) | 岛屿数量 | Time: O(m\*n) Space: O(m\*n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode200.java) [Go](go/src/problem/leetcode200/numIslands.go) | Medium | DFS BFS |
| 202 | [Happy Number](https://leetcode.com/problems/happy-number) | 快乐数 | Time: O(1) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode202.java) [Python](python/src/problem/leetcode/easy/leetcode_202.py) | Easy | Hash Table Two Pointers Math |
| 203 | [Remove Linked List Elements](https://leetcode.com/problems/remove-linked-list-elements) | 单链表删除数字 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode203.java) [Python](python/src/problem/leetcode/easy/leetcode_203.py) | Easy | Linked List |
| 204 | [Count Primes](https://leetcode.com/problems/count-primes) | 质数的个数 | Time: O(n\*log(log(n))) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode204.java) [Python](python/src/problem/leetcode/easy/leetcode_204.py) | Easy | Math |
| 205 | [Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings) | 同构字符串 | Time: O(1) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode205.java) | Easy | String |
| 206 | [Reverse Linked List](https://leetcode.com/problems/reverse-linked-list) | 反转链表 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode206.java) [Python](python/src/problem/leetcode/easy/leetcode_206.py) | Easy | Linked List |
| 207 | [Course Schedule](https://leetcode.com/problems/course-schedule) | 课程表 | Time: O(V+E) Space: O(V+E) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode207.java) | Medium | Graph Backtracking Topological Sort DFS BFS |
| 208 | [Implement Trie (Prefix Tree)](https://leetcode.com/problems/implement-trie-prefix-tree) | 实现前缀树 | Time: O(V+E) Space: O(V+E) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode208.java) | Medium | Design Trie |
| 209 | [Minimum Size Subarray Sum](https://leetcode.com/problems/minimum-size-subarray-sum) | 长度最小的子数组 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode209.java) | Medium | Two Pointers Binary Search Array |
| 210 | [Course Schedule II](https://leetcode.com/problems/course-schedule-ii) | 上课顺序 | Time: O(V+E) Space: O(V+E) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode210.java) | Medium | Graph Backtracking Topological Sort DFS BFS |
| 213 | [House Robber II](https://leetcode.com/problems/house-robber-ii) | 抢劫环形房子 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode213.java) | Medium | Dynamic Programming |
| 215 | [Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array) | 数组中第 K 大的元素 | Time: O(n\*log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode215.java) [Go](go/src/problem/leetcode215/findKthLargest.go) | Medium | Divide and Conquer Heap Array Sorting Quick Select |
| 217 | [Contains Duplicate](https://leetcode.com/problems/contains-duplicate/submissions) | 存在重复元素 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode217.java) [Python](python/src/problem/leetcode/easy/leetcode_217.py) | Easy | Array Hash Table Sort |
| 218 | [The Skyline Problem](https://leetcode.com/problems/the-skyline-problem) | 寻找天际线 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode218.java) | Hard | Divide and Conquer Heap Segment Tree |
| 220 | [Contains Duplicate III](https://leetcode-cn.com/problems/contains-duplicate-iii) | 存在重复元素 III | Time: O(n) Space: O(min(n, k)) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode220.java) | Medium | Sort Hash Table |
| 221 | [Maximal Square](https://leetcode.com/problems/maximal-square) | 最大正方形 | Time: O(m\*n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode221.java) [Go](go/src/problem/leetcode221/maximalSquare.go) | Medium | Dynamic Programming Array Stack |
| 224 | [Basic Calculator](https://leetcode.com/problems/basic-calculator) | 基本计算器 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode224.java) | Hard | Math Stack |
| 226 | [Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree) | 翻转二叉树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode226.java) [Python](python/src/problem/leetcode/easy/leetcode_226.py) | Easy | Tree |
| 227 | [Basic Calculator II](https://leetcode.com/problems/basic-calculator-ii) | 基本计算器 II | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode227.java) | Medium | String |
| 228 | [Summary Ranges](https://leetcode.com/problems/summary-ranges) | 汇总区间 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode228.java) | Easy | Array |
| 230 | [Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst) | 二叉搜索树中第 K 小的元素 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode230.java) | Medium | Tree Binary Search |
| 231 | [Power of Two](https://leetcode.com/problems/power-of-two) | 2 的幂 | Time: O(1) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode231.java) [Python](python/src/problem/leetcode/easy/leetcode_231.py) | Easy | Math Bit Manipulation |
| 232 | [Implement Queue using Stacks](https://leetcode.com/problems/implement-queue-using-stacks) | 用栈实现队列 | | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode232.java) [Python](python/src/problem/leetcode/easy/leetcode_232.py) | Easy | Stack Design |
| 234 | [Palindrome Linked List](https://leetcode.com/problems/palindrome-linked-list) | 回文链表 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode234.java) [Python](python/src/problem/leetcode/easy/leetcode_234.py) | Easy | Linked List Two Pointers |
| 235 | [Lowest Common Ancestor of a Binary Search Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree) | 二叉搜索树的最近公共祖先 | Time: O(h) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode235.java) [Python](python/src/problem/leetcode/easy/leetcode_235.py) | Easy | Tree |
| 236 | [Lowest Common Ancestor of a Binary Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree) | 二叉树的最近公共祖先 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode236.java) [Go](go/src/problem/leetcode236/lowestCommonAncestor.go) | Medium | Tree |
| 237 | [Delete Node in a Linked List](https://leetcode.com/problems/delete-node-in-a-linked-list) | 删除链表中的节点 | Time: O(1) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode237.java) [Python](python/src/problem/leetcode/easy/leetcode_237.py) | Easy | Linked List |
| 238 | [Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self) | 除了自身元素的数组乘积 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode238.java) | Medium | Array |
| 239 | [Sliding Window Maximum](https://leetcode.com/problems/sliding-window-maximum) | 滑动窗口最大值 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode239.java) | Hard | Heap |
| 240 | [Search a 2D Matrix II](https://leetcode.com/problems/search-a-2d-matrix-ii) | 行列递增的二维数组搜索 | Time: O(m+n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode240.java) [Go](go/src/problem/leetcode240/searchMatrix.go) | Medium | Binary Search Divide and Conquer |
| 242 | [Valid Anagram](https://leetcode.com/problems/valid-anagram/submissions) | 变位词校验 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode242.java) [Python](python/src/problem/leetcode/easy/leetcode_242.py) | Easy | String Sort Hash Table |
| 252 | [Meeting Rooms](https://leetcode.com/problems/meeting-rooms) | 会议室 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode252.java) | Easy | Sort |
| 253 | [Meeting Rooms II](https://leetcode.com/problems/meeting-rooms-ii) | 会议室 II | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode252.java) | Easy | Sort Line Sweep Greedy Heap |
| 255 | [Verify Preorder Sequence in Binary Search Tree](https://leetcode.com/problems/verify-preorder-sequence-in-binary-search-tree) | 验证前序遍历序列二叉搜索树 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode255.java) | Medium | Tree Stack Divide and Conquer |
| 256 | [Paint House](https://leetcode.com/problems/paint-house) | 粉刷房子 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode256.java) [Python](python/src/problem/leetcode/easy/leetcode_256.py) [Go](go/src/problem/leetcode256/minCost.go) | Easy | Dynamic Programming |
| 257 | [Binary Tree Paths](https://leetcode.com/problems/binary-tree-paths) | 二叉树的所有路径 | Time: O(n^2) Space: O(n^2) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode257.java) [Python](python/src/problem/leetcode/easy/leetcode_257.py) | Easy | Tree |
| 260 | [Single Number III](https://leetcode.com/problems/single-number-iii) | 只出现一次的两个数字 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode260.java) | Medium | Bit Manipulation |
| 263 | [Ugly Number](https://leetcode.com/problems/ugly-number) | 丑数 | Time: O(log2(n)+log3(n)+log5(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode263.java) [Python](python/src/problem/leetcode/easy/leetcode_263.py) | Easy | Math |
| 264 | [Ugly Number II](https://leetcode.com/problems/ugly-number-ii) | 丑数 II | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode264.java) | Medium | Heap Math Dynamic Programming |
| 268 | [Missing Number](https://leetcode.com/problems/missing-number) | 丢失的数字 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode268.java) | Medium | Array Math Bit Manipulation |
| 278 | [First Bad Version](https://leetcode.com/problems/first-bad-version) | 第一个出错的版本 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode278.java) [Python](python/src/problem/leetcode/easy/leetcode_278.py) | Easy | Binary Search |
| 283 | [Move Zeroes](https://leetcode.com/problems/move-zeroes) | 移动零 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode283.java) [Python](python/src/problem/leetcode/easy/leetcode_283.py) | Easy | Array Two Pointers |
| 287 | [Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number) | 寻找重复数 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode287.java) | Medium | Array Two Pointers Binary Search |
| 290 | [Word Pattern](https://leetcode.com/problems/word-pattern) | 单词规律 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode290.java) | Easy | Hash Table |
| 292 | [Nim Game](https://leetcode.com/problems/nim-game) | Nim 游戏 | Time: O(1) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode292.java) | Easy | Brainteaser Minimax |
| 295 | [Find Median from Data Stream](https://leetcode.com/problems/find-median-from-data-stream) | 数据流的中位数 | Time: O(log(n)) (add), O(1) (find) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode295.java) | Hard | Heap Design |
| 297 | [Serialize and Deserialize Binary Tree](https://leetcode.com/problems/serialize-and-deserialize-binary-tree) | 二叉树的序列化与反序列化 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode297.java) | Hard | Tree Design |
| 300 | [Longest Increasing Subsequence](https://leetcode.com/problems/longest-increasing-subsequence) | 最长上升子序列 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode300.java) [Go](go/src/problem/leetcode300/lengthOfLIS.go) | Medium | Binary Search Dynamic Programming |
| 303 | [Range Sum Query - Immutable](https://leetcode.com/problems/range-sum-query-immutable) | 区域和检索 - 数组不可变 | Time: O(1) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode303.java) [Python](python/src/problem/leetcode/easy/leetcode_303.py) [Go](go/src/problem/leetcode303/NumArray.go) | Easy | Array Dynamic Programming |
| 304 | [Range Sum Query 2D](https://leetcode.com/problems/range-sum-query-2d-immutable/submissions) | 二维区域和检索 - 矩阵不可变 | Time: O(m\*n) Space: O(m\*n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode304.java) [Python](python/src/problem/leetcode/medium/leetcode_304.py) [Go](go/src/problem/leetcode304/NumMatrix.go) | Medium | Array Dynamic Programming |
| 309 | [Best Time to Buy and Sell Stock with Cooldown](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown) | 最佳买卖股票时机含冷冻期 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode309.java) | Medium | Dynamic Programming |
| 310 | [Minimum Height Trees](https://leetcode.com/problems/minimum-height-trees) | 最小高度树 | Time: O(n^2) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode310.java) | Medium | Graph BFS DFS |
| 312 | [Burst Balloons](https://leetcode.com/problems/burst-balloons) | 戳气球 | Time: O(n^3) Space: O(n^2) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode312.java) | Hard | Dynamic Programming Divide and Conquer |
| 315 | [Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self) | 计算右侧小于当前元素的个数 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode315.java) | Hard | Binary Search Divide and Conquer Sort Binary Indexed Tree Segment Tree |
| 322 | [Coin Change](https://leetcode.com/problems/coin-change) | 零钱兑换 | Time: O(n\*sum) Space: O(sum) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode322.java) | Medium | Dynamic Programming |
| 326 | [Power of Three](https://leetcode.com/problems/power-of-three) | 3 的幂 | Time: O(1) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode326.java) [Python](python/src/problem/leetcode/easy/leetcode_326.py) | Easy | Math |
| 328 | [Odd Even Linked List](https://leetcode.com/problems/odd-even-linked-list) | 奇偶链表 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode328.java) | Medium | Linked List |
| 329 | [Longest Increasing Path in a Matrix](https://leetcode.com/problems/longest-increasing-path-in-a-matrix) | 矩阵中的最长递增路径 | Time: O(m\*n) Space: O(m\*n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode329.java) | Hard | DFS Topological Sort Memoization |
| 338 | [Counting Bits](https://leetcode.com/problems/counting-bits) | 连续自然数二进制中 1 的个数 | Time: O(k) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode338.java) | Medium | Dynamic Programming Bit Manipulation |
| 332 | [Reconstruct Itinerary](https://leetcode.com/problems/reconstruct-itinerary) | 重新安排行程 | Time: O(n*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode332.java) | Medium | Graph DFS |
| 337 | [House Robber III](https://leetcode.com/problems/house-robber-iii) | 打家劫舍 III | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode337.java) | Medium | Tree DFS |
| 344 | [Reverse String](https://leetcode.com/problems/reverse-string) | 反转字符串 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode344.java) [Python](python/src/problem/leetcode/easy/leetcode_344.py) | Easy | String Two Pointers |
| 347 | [Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements) | 前 K 个高频数字 | Time(avg): O(n) Time(worst): O(n^2) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode347.java) | Medium | Hash Table Heap Sort |
| 349 | [Intersection Of Two Arrays](https://leetcode.com/problems/intersection-of-two-arrays) | 两个数组的交集 | Time: O(m+n) Space: O(m+n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode349.java) | Easy | Sort Hash Table Two Pointers Binary Search |
| 350 | [Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii) | 两个数组的交集 II | Time: O(m+n) Space: O(m+k) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode350.java) [Python](python/src/problem/leetcode/easy/leetcode_350.py) | Easy | Hash Table Two Pointers Sort |
| 354 | [Russian Doll Envelopes](https://leetcode.com/problems/russian-doll-envelopes) | 俄罗斯套娃信封问题 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode354.java) | Hard | Dynamic Programming Binary Search |
| 365 | [Water and Jug Problem](https://leetcode-cn.com/problems/water-and-jug-problem) | 水壶问题 | Time: O(log(min(x,y))) S Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode365.java) | Medium | DFS Math |
| 367 | [Valid Perfect Square](https://leetcode.com/problems/valid-perfect-square) | 验证完全平方数 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode367.java) [Python](python/src/problem/leetcode/easy/leetcode_367.py) | Easy | Math Binary Search |
| 369 | [Plus One Linked List](https://leetcode.com/problems/plus-one-linked-list) | 链表加一 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode369.java) | Medium | Linked List |
| 371 | [Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers/description) | 不用 +/- 求两数之和 | Time: O(m) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode371.java) [Python](python/src/problem/leetcode/easy/leetcode_371.py) | Easy | Bit Manipulation |
| 373 | [Find K Pairs with Smallest Sums](https://leetcode.com/problems/find-k-pairs-with-smallest-sums) | 查找和最小的K对数字 | Time: O(k\*log(k)) Space: O(k) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode373.java) | Medium | Heap |
| 376 | [Wiggle Subsequence](https://leetcode.com/problems/wiggle-subsequence/submissions) | 摆动序列 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode376.java) [Python](python/src/problem/leetcode/medium/leetcode_376.py) [Go](go/src/problem/leetcode376/wiggleMaxLength.go) | Medium | Dynamic Programming Greedy |
| 377 | [Combination Sum IV](https://leetcode.com/problems/combination-sum-iv) | 摆动序列 | Time: O(k\*n), Space: O(k) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode377.java) | Medium | Dynamic Programming |
| 378 | [Kth Smallest Element in a Sorted Matrix](https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix) | 有序矩阵中第 K 小的元素 | Time: O(k\*log(k)) Space: O(k) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode378.java) [Go](go/src/problem/leetcode378/kthSmallest.go) | Medium | Heap Binary Search |
| 380 | [Insert Delete GetRandom O(1)](https://leetcode.com/problems/insert-delete-getrandom-o1) | 常数时间插入、删除和获取随机元素 | Time: O(1) Time: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode380.java) | Medium | Design Hash Table Array |
| 382 | [Linked List Random Node](https://leetcode.com/problems/linked-list-random-node) | 链表随机节点 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode382.java) | Medium | Reservoir Sampling |
| 384 | [Shuffle an Array](https://leetcode.com/problems/shuffle-an-array) | 随机洗牌 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode384.java) | Medium | Array |
| 386 | [Lexicographical Numbers](https://leetcode.com/problems/lexicographical-numbers) | 字典序排数 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode386.java) | Medium | DFS Tree |
| 387 | [First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string) | 字符串中的第一个唯一字符 | Time: O(n) Space: O(m) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode387.java) [Python](python/src/problem/leetcode/easy/leetcode_387.py) | Easy | String Hash Table |
| 389 | [Find the Difference](https://leetcode.com/problems/find-the-difference) | 找不同 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode389.java) | Easy | Hash Table Bit Manipulation |
| 399 | [Evaluate Division](https://leetcode.com/problems/evaluate-division/submissions) | 除法求值 | Time: O(m\*V) Space: O(V+E) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode399.java) | Medium | Graph |
| 402 | [Remove K Digits](https://leetcode.com/problems/remove-k-digits) | 移掉 K 位数字 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode402.java) | Hard | Stack Greedy |
| 403 | [Frog Jump](https://leetcode.com/problems/frog-jump) | 青蛙过河 | Time: O(n^2) Space: O(n^2) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode403.java) | Hard | Dynamic Programming |
| 406 | [Queue Reconstruction by Height](https://leetcode.com/problems/queue-reconstruction-by-height) | 根据身高重建队列 | Time: O(n) Space: O(n\*log(n)) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode406.java) | Medium | Greedy |
| 407 | [Trapping Rain Water II](https://leetcode.com/problems/trapping-rain-water-ii) | 接雨水 II | Time: O(m\*n) Space: O(m\*n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode407.java) | Hard | BFS Heap |
| 409 | [Longest Palindrome](https://leetcode.com/problems/longest-palindrome) | 最长回文串 | Time: O(n) Space: O(m) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode409.java) [Python](python/src/problem/leetcode/easy/leetcode_409.py) | Easy | Hash Table |
| 414 | [Third Maximum Number](https://leetcode.com/problems/third-maximum-number) | 第三大的数 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode414.java) [Python](python/src/problem/leetcode/easy/leetcode_414.py) | Easy | Array |
| 415 | [Add Strings](https://leetcode.com/problems/add-strings) | 字符串相加 | Time: O(m+n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode415.java) [Python](python/src/problem/leetcode/easy/leetcode_415.py) [Go](go/src/problem/leetcode415/addStrings.go) | Easy | String |
| 416 | [Partition Equal Subset Sum](https://leetcode.com/problems/partition-equal-subset-sum) | 分割等和子集 | Time: O(target\*n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode416.java) | Medium | Dynamic Programming |
| 424 | [Longest Repeating Character Replacement](https://leetcode.com/problems/longest-repeating-character-replacement) | 替换后的最长重复字符 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode424.java) | Medium | Two Pointers Sliding Window |
| 426 | [Convert Binary Search Tree To Sorted Doubly Linked List](https://leetcode.com/problems/convert-binary-search-tree-to-sorted-doubly-linked-list) | 将二叉搜索树转化为排序的双向链表 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode426.java) | Medium | Tree Linked List |
| 437 | [Path Sum III](https://leetcode.com/problems/path-sum-iii) | 路径总和 III | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode437.java) | Medium | Tree |
| 438 | [Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string) | 查找字符串中所有变位词 | Time: O(n) Space: O(k) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode438.java) | Medium | Hash Table String |
| 440 | [K-th Smallest in Lexicographical Order](https://leetcode.com/problems/k-th-smallest-in-lexicographical-order) | 字典序的第 K 小数字 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode440.java) [Go](go/src/problem/leetcode440/findKthNumber.go) | Hard | Tree |
| 443 | [String Compression](https://leetcode.com/problems/string-compression) | 压缩字符串 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode443.java) [Python](python/src/problem/leetcode/easy/leetcode_443.py) | Easy | String Two Pointers |
| 445 | [Add Two Numbers II](https://leetcode.com/problems/add-two-numbers-ii) | 两数相加 II | Time: O(max(m,n)) Space: O(m+n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode445.java) [Go](go/src/problem/leetcode445/addTwoNumbers.go) | Medium | Linked List |
| 447 | [Number of Boomerangs](https://leetcode.com/problems/number-of-boomerangs/solution/hui-xuan-biao-de-shu-liang-by-leetcode-s-lft5) | 回旋镖的数量 | Time: O(n^2) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode447.java) | Medium | Math Hash Table Array |
| 448 | [Find All Numbers Disappeared in an Array](https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array) | 找到所有数组中消失的数字 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode448.java) [Python](python/src/problem/leetcode/easy/leetcode_448.py) | Easy | Array |
| 449 | [Serialize and Deserialize BST](https://leetcode.com/problems/serialize-and-deserialize-bst) | 序列化和反序列化二叉搜索树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode449.java) | Medium | Tree |
| 450 | [Delete Node in a BST](https://leetcode.com/problems/delete-node-in-a-bst) | 二叉搜索树中删除节点 | Time: O(h) Space: O(h) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode450.java) | Medium | Tree |
| 454 | [4Sum II](https://leetcode.com/problems/4sum-ii) | 四数相加 II | Time: O(n^2) Space: O(n^2) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode454.java) | Medium | Hash Table Binary Search |
| 455 | [Assign Cookies](https://leetcode.com/problems/assign-cookies) | 分发饼干 | Time: O(n\*log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode455.java) | Easy | Greedy |
| 460 | [LFU Cache](https://leetcode.com/problems/lfu-cache) | LFU 缓存 | Time: O(1) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode460.java) | Hard | Design |
| 461 | [Hamming Distance](https://leetcode.com/problems/hamming-distance) | 汉明距离 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode461.java) [Python](python/src/problem/leetcode/easy/leetcode_461.py) | Easy | Bit Manipulation |
| 463 | [Island Perimeter](https://leetcode.com/problems/island-perimeter) | 岛屿的周长 | Time: O(n^2) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode463.java) [Python](python/src/problem/leetcode/easy/leetcode_463.py) | Easy | Hash Table |
| 470 | [Implement Rand10() Using Rand7()](https://leetcode.com/problems/implement-rand10-using-rand7) | 用 Rand7() 实现 Rand10() | | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode470.java) | Medium | Math Random |
| 486 | [Predict the Winner](https://leetcode.com/problems/predict-the-winner) | 预测赢家 | Time: O(n^2) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode486.java) | Medium | Minimax Dynamic Programming |
| 493 | [Reverse Pairs](https://leetcode.com/problems/reverse-pairs) | 翻转对 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode493.java) | Hard | Binary Search Divided and Conquer Sort Binary Indexed Tree Segment Tree |
| 509 | [Fibonacci Number](https://leetcode.com/problems/fibonacci-number) | 斐波那契数 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode509.java) [Python](python/src/problem/leetcode/easy/leetcode_509.py) | Easy | Array Dynamic Programming |
| 518 | [Coin Change 2](https://leetcode.com/problems/coin-change-2) | 零钱兑换 II | Time: O(n\*sum) Space: O(sum) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode518.java) | Medium | Dynamic Programming |
| 523 | [Continuous Subarray Sum](https://leetcode.com/problems/continuous-subarray-sum) | 连续的子数组和 | Time: O(n) Space: O(k) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode523.java) [Python](python/src/problem/leetcode/medium/leetcode_523.py) | Medium | Math |
| 528 | [Random Pick with Weight](https://leetcode.com/problems/random-pick-with-weight) | 按权重随机选择 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode528.java) | Medium | Prefix Sum Binary Search Prefix Sum |
| 530 | [Minimum Absolute Difference in BST](https://leetcode.com/problems/convert-bst-to-greater-tree) | 二叉搜索树的最小绝对差 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode530.java) | Easy | Tree |
| 538 | [Convert BST to Greater Tree](https://leetcode.com/problems/convert-bst-to-greater-tree) | 把二叉搜索树转换为累加树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode538.java) [Python](python/src/problem/leetcode/easy/leetcode_538.py) | Easy | Tree |
| 540 | [Single Element in a Sorted Array](https://leetcode.com/problems/single-element-in-a-sorted-array) | 有序数组中的单身数字 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode540.java) | Medium | Bit Manipulation Binary Search |
| 543 | [Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree) | 二叉树的直径 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode543.java) [Python](python/src/problem/leetcode/easy/leetcode_543.py) [Go](go/src/problem/leetcode543/diameterOfBinaryTree.go) | Easy | Tree |
| 547 | [Number of Provinces](https://leetcode.com/problems/number-of-provinces) | 省份数量 | Time: O(n^2) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode547.java) | Medium | DFS Union Find |
| 554 | [Brick Wall](https://leetcode-cn.com/problems/brick-wall) | 砖墙 | Time: O(m\*n) Space: O(m\*n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode554.java) | Medium | Hash Table |
| 556 | [Next Greater Element III](https://leetcode.com/problems/next-greater-element-iii) | 下一个更大元素 III | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode556.java) | Medium | String |
| 557 | [Reverse Words in a String III](https://leetcode.com/problems/reverse-words-in-a-string-iii) | 反转字符串中的单词 III | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode557.java) [Python](python/src/problem/leetcode/easy/leetcode_557.py) | Easy | String |
| 558 | [Quad Tree Intersection](https://leetcode.com/problems/quad-tree-intersection) | 四叉树交集 | Time: O(n^4) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode558.java) [Python](python/src/problem/leetcode/easy/leetcode_558.py) | Easy | Tree |
| 560 | [Subarray Sum Equals K](https://leetcode.com/problems/subarray-sum-equals-k) | 和为 K 的子数组 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode560.java) | Medium | Hash Table Array |
| 566 | [Reshape the Matrix](https://leetcode.com/problems/reshape-the-matrix) | 重塑矩阵 | Time: O(r\*c) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode566.java) | Easy | Array |
| 567 | [Permutation in String](https://leetcode.com/problems/permutation-in-string) | 字符串的排列 | Time: O(n+m+∣Σ∣) Space: O(∣Σ∣) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode567.java) | Medium | Two Pointers Sliding Window String |
| 572 | [Subtree of Another Tree](https://leetcode.com/problems/subtree-of-another-tree) | 另一个树的子树 | Time: O(m\*n) Space: O(h) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode572.java) | Easy | Tree |
| 581 | [Shortest Unsorted Continuous Subarray](https://leetcode.com/problems/shortest-unsorted-continuous-subarray) | 需要排序的最短子数组 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode581.java) | Medium | Array |
| 605 | [Can Place Flowers](https://leetcode.com/problems/can-place-flowers) | 种花问题 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode605.java) | Easy | Array Greedy |
| 611 | [Valid Triangle Number](https://leetcode.com/problems/valid-triangle-number) | 有效三角形的个数 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode611.java) | Medium | Array Binary Search Two Pointers |
| 617 | [Merge Two Binary Trees](https://leetcode.com/problems/merge-two-binary-trees) | 合并二叉树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode617.java) [Python](python/src/problem/leetcode/easy/leetcode_617.py) | Easy | Tree |
| 621 | [Task Scheduler](https://leetcode.com/problems/task-scheduler) | 任务调度器 | Time: O(m) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode621.java) | Medium | Greedy Head Queue |
| 633 | [Sum of Square Numbers](https://leetcode.com/problems/sum-of-square-numbers) | 平方数之和 | Time: O(c^(1/2)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode633.java) [Python](python/src/problem/leetcode/easy/leetcode_633.py) | Easy | Math Hash Table Two Pointers |
| 647 | [Palindromic Substrings](https://leetcode.com/problems/palindromic-substrings) | 回文子串 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode647.java) | Medium | String Dynamic Programming |
| 649 | [Dota2 Senate](https://leetcode.com/problems/dota2-senate) | Dota2 参议院 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode649.java) | Medium | Greedy |
| 665 | [Non-decreasing Array](https://leetcode.com/problems/non-decreasing-array) | 非递减数列 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode665.java) [Python](python/src/problem/leetcode/easy/leetcode_665.py) | Easy | Array |
| 670 | [Maximum Swap](https://leetcode.com/problems/maximum-swap) | 最大交换 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode670.java) | Medium | Math Array |
| 673 | [Number of Longest Increasing Subsequence](https://leetcode.com/problems/number-of-longest-increasing-subsequence) | 最长递增子序列的个数 | Time: O(n\*log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode673.java) | Medium | Dynamic Programming |
| 674 | [Longest Continuous Increasing Subsequence](https://leetcode.com/problems/longest-continuous-increasing-subsequence) | 最长连续递增序列 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode674.java) | Easy | Array |
| 678 | [Valid Parenthesis String](https://leetcode.com/problems/valid-parenthesis-string) | 有效的括号字符串 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode678.java) | Medium | String |
| 684 | [Redundant Connection](https://leetcode.com/problems/redundant-connection) | 冗余连接 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode684.java) | Medium | Union Find Graph Tree |
| 690 | [Employee Importance](https://leetcode-cn.com/problems/employee-importance) | 员工的重要性 | Time: O(n) Space: (n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode690.java) | Easy | DFS BFS Hash Table |
| 695 | [Max Area of Island](https://leetcode.com/problems/max-area-of-island) | 岛屿的最大面积 | Time: O(R\*C) Space: (R\*C) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode695.java) | Medium | DFS Array Union Find |
| 697 | [Degree of an Array](https://leetcode.com/problems/degree-of-an-array) | 数组的度 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode697.java) [Go](go/src/problem/leetcode697/findShortestSubArray.go) | Easy | Array Hash Table |
| 700 | [Search in a Binary Search Tree](https://leetcode.com/problems/search-in-a-binary-search-tree) | 二叉搜索树中查找数字 | Time: O(h) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode700.java) [Python](python/src/problem/leetcode/easy/leetcode_700.py) | Easy | Tree |
| 703 | [Kth Largest Element in a Stream](https://leetcode.com/problems/kth-largest-element-in-a-stream) | 数据流中第 K 大的元素 | Time: O(n\*log(k)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode703.java) [Python](python/src/problem/leetcode/easy/leetcode_703.py) | Easy | Heap |
| 704 | [Binary Search](https://leetcode.com/problems/binary-search) | 二分搜索 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode704.java) [Python](python/src/problem/leetcode/easy/leetcode_704.py) | Easy | Binary Search |
| 706 | [Design HashMap](https://leetcode-cn.com/problems/design-hashmap) | 设计哈希映射 | Time: O(n/b) Space: O(n+b) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode706.java) | Easy | Hash Table Linked List Design |
| 714 | [Best Time to Buy and Sell Stock with Transaction Fee](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-transaction-fee) | 买卖股票的最佳时机含手续费 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode714.java) | Medium | Greedy Array Dynamic Programming |
| 718 | [Maximum Length of Repeated Subarray](https://leetcode-cn.com/problems/maximum-length-of-repeated-subarray) | 最长重复子数组 | Time: O((M+N)\*log(min(M,N))) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode718.java) | Medium | Binary Search Hash Table Array Dynamic Programming |
| 719 | [Find K-th Smallest Pair Distance](https://leetcode.com/problems/find-k-th-smallest-pair-distance) | 找出第 k 小的距离对 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode719.java) | Hard | Heap Array Binary Search |
| 721 | [Accounts Merge](https://leetcode.com/problems/accounts-merge) | 账户合并 | Time: O(n\*log(n)) Space: O(n\*log(n)) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode721.java) | Medium | DFS Union Find |
| 724 | [Find Pivot Index](https://leetcode.com/problems/find-pivot-index/submissions) | 寻找数组的平衡点 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode724.java) [Python](python/src/problem/leetcode/easy/leetcode_724.py) | Easy | Array |
| 738 | [Monotone Increasing Digits](https://leetcode.com/problems/monotone-increasing-digits) | 单调递增的数字 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode738.java) | Medium | Greedy |
| 739 | [Daily Temperatures](https://leetcode.com/problems/daily-temperatures) | 每日温度 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode739.java) | Medium | Array Stack |
| 746 | [Min Cost Climbing Stairs](https://leetcode.com/problems/min-cost-climbing-stairs) | 爬楼梯的最小代价 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode746.java) [Python](python/src/problem/leetcode/easy/leetcode_746.py) | Easy | Array Dynamic Programming |
| 752 | [Open the Lock](https://leetcode.com/problems/open-the-lock) | 打开转盘锁 | Time: O(N^2\*A^N+D) Space: O(A^N+D) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode752.java) | Medium | BFS |
| 754 | [Reach a Number](https://leetcode.com/problems/reach-a-number) | 到达终点数字 | Time: O(1) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode754.java) | Medium | Math |
| 767 | [Reorganize String](https://leetcode.com/problems/reorganize-string) | 重构字符串 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode767.java) | Medium | Greedy Heap String |
| 771 | [Jewels and Stones](https://leetcode.com/problems/jewels-and-stones) | 石头中的珠宝数量 | Time: O(m+n) Space: O(k) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode771.java) [Python](python/src/problem/leetcode/easy/leetcode_771.py) | Easy | Hash Table |
| 773 | [Sliding Puzzle](https://leetcode.com/problems/sliding-puzzle) | 滑动谜题 | Time: O(R\*C\*(R\*C)!) Space: O(R\*C\*(R\*C)!) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode773.java) | Hard | BFS |
| 781 | [Rabbits in Forest](https://leetcode.com/problems/rabbits-in-forest) | 森林中的兔子 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode781.java) | Medium | Math Hash Table |
| 783 | [Minimum Distance Between BST Nodes](https://leetcode.com/problems/minimum-distance-between-bst-nodes) | 二叉搜索树节点最小距离 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode783.java) | Easy | Tree DFS |
| 785 | [Is Graph Bipartite](https://leetcode.com/problems/is-graph-bipartite) | 判断二分图 | Time: O(V+E) Space: O(V) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode785.java) | Medium | Graph DFS BFS |
| 796 | [Rotate String](https://leetcode.com/problems/rotate-string) | 旋转字符串 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode796.java) | Easy | String Two Pointers Quick Select |
| 801 | [Minimum Swaps To Make Sequences Increasing](https://leetcode.com/problems/minimum-swaps-to-make-sequences-increasing) | 使序列递增的最小交换次数 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode801.java) | Medium | Dynamic Programming |
| 820 | [Short Encoding Of Words](https://leetcode.com/problems/short-encoding-of-words) | 单词的压缩编码 | Time: O(∑wi) Space: O(S\*∑wi) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode820.java) | Medium | Trie Hash Table |
| 830 | [Positions of Large Groups](https://leetcode.com/problems/positions-of-large-groups) | 较大分组的位置 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode830.java) | Easy | Array |
| 842 | [Split Array into Fibonacci Sequence](https://leetcode.com/problems/split-array-into-fibonacci-sequence) | 将数组拆分成斐波那契序列 | Time: *O*(n\*log2C) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode842.java) | Medium | Greedy Backtracking String |
| 860 | [Lemonade Change](https://leetcode.com/problems/lemonade-change) | 柠檬水找零 | Time: *O*(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode860.java) | Easy | Greedy |
| 861 | [Score After Flipping Matrix](https://leetcode.com/problems/score-after-flipping-matrix) | 翻转矩阵后的得分 | Time: O(m\*n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode861.java) | Medium | Greedy |
| 867 | [Transpose Matrix](https://leetcode.com/problems/transpose-matrix) | 转置矩阵 | Time: O(m\*n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode867.java) [Go](go/src/problem/leetcode867/transpose.go) | Easy | Array |
| 876 | [Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list) | 单链表中间节点 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode876.java) [Python](python/src/problem/leetcode/easy/leetcode_876.py) | Easy | Linked List |
| 887 | [Super Egg Drop](https://leetcode.com/problems/super-egg-drop) | 鸡蛋掉落 | Time: O(K\*N^(1/K)) Space: O(K\*N) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode887.java) | Hard | Math Binary Search Dynamic Programming |
| 892 | [Surface Area of 3D Shapes](https://leetcode.com/problems/surface-area-of-3d-shapes) | 三维形体的表面积 | Time: O(n^2) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode892.java) [Python](python/src/problem/leetcode/easy/leetcode_892.py) | Easy | Geometry Math |
| 896 | [Monotonic Array](https://leetcode.com/problems/monotonic-array) | 单调数列 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode896.java) [Go](go/src/problem/leetcode896/isMonotonic.go) | Easy | Array |
| 897 | [Increasing Order Search Tree](https://leetcode.com/problems/increasing-order-search-tree) | 递增顺序搜索树 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode897.java) | Easy | Tree DFS |
| 912 | [Sort an Array](https://leetcode.com/problems/sort-an-array) | 排序数组 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode912.java) | Medium | Array Sort |
| 938 | [Range Sum of BST](https://leetcode.com/problems/range-sum-of-bst/submissions) | 二叉搜索树的范围和 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode938.java) [Python](python/src/problem/leetcode/easy/leetcode_938.py) | Easy | Tree |
| 945 | [ Minimum Increment to Make Array Unique](https://leetcode.com/problems/minimum-increment-to-make-array-unique) | 使数组唯一的最小增量 | Time: O(log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode945.java) | Medium | Array |
| 946 | [Validate Stack Sequences](https://leetcode.com/problems/validate-stack-sequences) | 验证入栈出栈序列 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode946.java) | Medium | Stack |
| 947 | [Most Stones Removed with Same Row or Column](https://leetcode.com/problems/most-stones-removed-with-same-row-or-column) | 移除最多的同行或同列石头 | Time: O(n\*log(A)) Space: O(A) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode947.java) | Medium | DFS Union Find |
| 973 | [K Closest Points to Origin](https://leetcode.com/problems/k-closest-points-to-origin) | 最接近原点的 K 个点 | Time: O(n\*log(K)) Space: O(K) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode973.java) | Medium | Heap Sort Divide and Conquer Quick Select |
| 976 | [Largest Perimeter Triangle](https://leetcode.com/problems/largest-perimeter-triangle) | 三角形的最大周长 | Time: O(n\*log(n)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode976.java) | Easy | Sort Math |
| 977 | [Squares of a Sorted Array](https://leetcode.com/problems/squares-of-a-sorted-array) | 有序数组的平方 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode977.java) | Easy | Two Pointers Array |
| 978 | [Longest Turbulent Subarray](https://leetcode.com/problems/longest-turbulent-subarray) | 最长湍流子数组 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode978.java) | Medium | Array Dynamic Programming Sliding Window |
| 992 | [Subarrays with K Different Integers](https://leetcode.com/problems/subarrays-with-k-different-integers) | K 个不同整数的子数组 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/hard/LeetCode992.java) | Hard | Sliding Window Hash Table Two Pointers |
| 1004 | [Max Consecutive Ones III](https://leetcode.com/problems/max-consecutive-ones-iii) | 最大连续1的个数 III | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode1004.java) [Go](go/src/problem/leetcode1004/longestOnes.go) | Medium | Two Pointers Sliding Window |
| 1006 | [Clumsy Factorial](https://leetcode.com/problems/clumsy-factorial) | 笨阶乘 | Time: O(1) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode1006.java) | Medium | Stack Math |
| 1018 | [Binary Prefix Divisible By 5](https://leetcode.com/problems/binary-prefix-divisible-by-5) | 可被 5 整除的二进制前缀 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1018.java) | Easy | Array |
| 1029 | [Two City Scheduling](https://leetcode.com/problems/two-city-scheduling) | 两地调度 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1029.java) [Python](python/src/problem/leetcode/easy/leetcode_1029.py) | Easy | Greedy |
| 1033 | [Moving Stones Until Consecutive](https://leetcode.com/problems/moving-stones-until-consecutive) | 移动石子直到连续 | Time: O(1)) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode1033.java) | Medium| Math |
| 1046 | [Last Stone Weight](https://leetcode.com/problems/last-stone-weight) | 最后一块石头的重量 | Time: O(n\*log(n)) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1046.java) | Easy | Greedy Heap |
| 1047 | [Remove All Adjacent Duplicates In String](https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string) | 删除字符串中的所有相邻重复项 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1047.java) | Easy | Stack |
| 1091 | [Shortest Path in Binary Matrix](https://leetcode.com/problems/shortest-path-in-binary-matrix) | 二进制矩阵中的最短路径 | Time: O(R\*C) Space: O(R\*C) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode1091.java) | Medium | BFS |
| 1114 | [Print in Order](https://leetcode.com/problems/print-in-order) | 按序打印 | | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1114.java) | Easy | Concurrency |
| 1116 | [Print Zero Even Odd](https://leetcode.com/problems/print-zero-even-odd) | 打印零与奇偶数 | | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode1116.java) | Medium | Concurrency |
| 1143 | [Longest Common Subsequence](https://leetcode.com/problems/longest-common-subsequence) | 最长公共子序列 | | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode1143.java) | Medium | Dynamic Programming |
| 1232 | [Check If It Is a Straight Line](https://leetcode.com/problems/check-if-it-is-a-straight-line) | 缀点成线 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1232.java) | Easy | Math Geometry Array |
| 1304 | [Find N Unique Integers Sum up to Zero](https://leetcode.com/problems/find-n-unique-integers-sum-up-to-zero) | 和为零的 N 个唯一整数 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1304.java) [Python](python/src/problem/leetcode/easy/leetcode_1304.py) | Easy | Array |
| 1430 | [Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit](https://leetcode.com/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit) | 绝对差不超过限制的最长连续子数组 | Time: O(n) Space: O(n) | [Java](java/src/main/java/com/ywh/problem/leetcode/medium/LeetCode1430.java) | Medium | Array Sliding Window |
| 1480 | [Running Sum of 1d array](https://leetcode-cn.com/problems/running-sum-of-1d-array) | 一维数组的动态和 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1480.java) | Easy | Array Prefix Sum |
| 1588 | [Sum of all odd length subarrays](https://leetcode.com/problems/sum-of-all-odd-length-subarrays) | 所有奇数长度子数组的和 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode1588.java) | Easy | Array Prefix Sum Math |
| 2351 | [First letter to appear twice](https://leetcode/problems/first-letter-to-appear-twice) | 第一个出现两次的字母 | Time: O(n) Space: O(1) | [Java](java/src/main/java/com/ywh/problem/leetcode/easy/LeetCode2351.java) | Easy | Hash Table String |

## Interview (9)

### 《程序员代码面试指南》

#### Stack & Queue

| No. | Title | Solution | Difficulty |
| ---- | -------------------------- | ------------------------------------------------------------ | ---------- |
| 1 | 设计一个有 getMin 功能的栈 | [Python](python/src/problem/interview/chapter1/get_min_stack.py) | 1 |
| 2 | 用一个栈实现另一个栈的排序 | [Python](python/src/problem/interview/chapter1/sort_stack_by_stack.py) | 1 |
| 4 | 猫狗队列 | [Python](python/src/problem/interview/chapter1/pet_queue.py) | 1 |
| 5 | 生成窗口最大值数组 | [Python](python/src/problem/interview/chapter1/get_max_window.py) | 2 |

#### Linked List

| No. | Title | Solution | Difficulty |
| ---- | ------------------------------------- | ------------------------------------------------------------ | ---------- |
| 1 | 打印两个有序链表的公共部分 | [Java](java/src/main/java/com/ywh/problem/interview/chapter2/RemoveLastKthNode.java) | 1 |
| 2 | 在单链表和双链表中删除倒数第 k 个节点 | [Java](java/src/main/java/com/ywh/problem/interview/chapter2/RemoveLastKthNode.java) | 1 |
| 3 | 删除链表的中间节点和 a/b 处的节点 | [Java](java/src/main/java/com/ywh/problem/interview/chapter2/RemoveByRatio.java) | 1 |
| 4 | 反转单向和双向链表 | [Java](java/src/main/java/com/ywh/problem/interview/chapter2/ReverseList.java) | 1 |
| 5 | 反转部分单项链表 | [Java](java/src/main/java/com/ywh/problem/interview/chapter2/ReversePart.java) | 1 |

## Usage

### Java
```bash
mvn test [-Dtest=ClassName]
```

### C

```shell
mkdir build
cd build && cmake ../
make
```

### Python

...

### Go

...

## Thanks

Thanks for JetBrains' support ([Free Open Source Licenses](https://www.jetbrains.com/community/opensource)). :heart:

[![](https://ywh-oss.oss-shenzhen.aliyuncs.com/blog/idea.svg "JetBrains")](https://www.jetbrains.com/?from=algorithm)

## License

See LICENSE file.

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