LeetCode in Go
source link: https://github.com/halfrost/LeetCode-Go
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LeetCode in Go
LeetCode Online Judge is a website containing many algorithm questions. Most of them are real interview questions of Google, Facebook, LinkedIn, Apple, etc. and it always help to sharp our algorithm Skills. Level up your coding skills and quickly land a job. This is the best place to expand your knowledge and get prepared for your next interview. This repo shows my solutions in Go with the code style strictly follows the Google Golang Style Guide. Please feel free to reference and STAR to support this repo, thank you!
支持 Progressive Web Apps 和 Dark Mode 的题解电子书《LeetCode Cookbook》 Online Reading
离线版本的电子书《LeetCode Cookbook》PDF Download here
通过 iOS / Android 浏览器安装 PWA 版《LeetCode Cookbook》至设备桌面随时学习
Data Structures
标识了
的专题是完成所有题目了的，没有标识的是还没有做完所有题目的
数据结构 变种 相关题目 讲解文章 顺序线性表：向量
单链表
1. 双向链表
2. 静态链表
3. 对称矩阵
4. 稀疏矩阵
哈希表
1. 散列函数
2. 解决碰撞/填充因子
栈和队列
1. 广义栈
2. 双端队列
队列
1. 链表实现
2. 循环数组实现
3. 双端队列
字符串
1. KMP算法
2. 有限状态自动机
3. 模式匹配有限状态自动机
4. BM 模式匹配算法
5. BM-KMP 算法
6. BF 算法
树
1. 二叉树
2. 并查集
3. Huffman 树
数组实现的堆
1. 极大堆和极小堆
2. 极大极小堆
3. 双端堆
4. d 叉堆
树实现的堆
1. 左堆
2. 扁堆
3. 二项式堆
4. 斐波那契堆
5. 配对堆
查找
1. 哈希表
2. 跳跃表
3. 排序二叉树
4. AVL 树
5. B 树 / B+ 树 / B* 树
6. AA 树
7. 红黑树
8. 排序二叉堆
9. Splay 树
10. 双链树
11. Trie 树
12. R 树
-------------------------------------------- -------------------------------------------------------------------------------------------- --------------------------- -----------------------------------
Algorithm
算法
具体类型
相关题目
讲解文章
排序算法
1. 冒泡排序
2. 插入排序
3. 选择排序
4. 希尔 Shell 排序
5. 快速排序
6. 归并排序
7. 堆排序
8. 线性排序算法
9. 自省排序
10. 间接排序
11. 计数排序
12. 基数排序
13. 桶排序
14. 外部排序 - k 路归并败者树
15. 外部排序 - 最佳归并树
递归与分治
1. 二分搜索/查找
2. 大整数的乘法
3. Strassen 矩阵乘法
4. 棋盘覆盖
5. 合并排序
6. 快速排序
7. 线性时间选择
8. 最接近点对问题
9. 循环赛日程表
动态规划
1. 矩阵连乘问题
2. 最长公共子序列
3. 最大子段和
4. 凸多边形最优三角剖分
5. 多边形游戏
6. 图像压缩
7. 电路布线
8. 流水作业调度
9. 0-1 背包问题/背包九讲
10. 最优二叉搜索树
11. 动态规划加速原理
12. 树型 DP
贪心
1. 活动安排问题
2. 最优装载
3. 哈夫曼编码
4. 单源最短路径
5. 最小生成树
6. 多机调度问题
回溯法
1. 装载问题
2. 批处理作业调度
3. 符号三角形问题
4. n 后问题
5. 0-1 背包问题
6. 最大团问题
7. 图的 m 着色问题
8. 旅行售货员问题
9. 圆排列问题
10. 电路板排列问题
11. 连续邮资问题
搜索
1. 枚举
2. DFS
3. BFS
4. 启发式搜索
随机化
1. 随机数
2. 数值随机化算法
3. Sherwood 舍伍德算法
4. Las Vegas 拉斯维加斯算法
5. Monte Carlo 蒙特卡罗算法
1. 计算 π 值
2. 计算定积分
3. 解非线性方程组
4. 线性时间选择算法
5. 跳跃表
6. n 后问题
7. 整数因子分解
8. 主元素问题
9. 素数测试
图论
1. 遍历 DFS / BFS
2. AOV / AOE 网络
3. Kruskal 算法(最小生成树)
4. Prim 算法(最小生成树)
5. Boruvka 算法(最小生成树)
6. Dijkstra 算法(单源最短路径)
7. Bellman-Ford 算法(单源最短路径)
8. SPFA 算法(单源最短路径)
9. Floyd 算法(多源最短路径)
10. Johnson 算法(多源最短路径)
11. Fleury 算法(欧拉回路)
12. Ford-Fulkerson 算法(最大网络流增广路)
13. Edmonds-Karp 算法(最大网络流)
14. Dinic 算法(最大网络流)
15. 一般预流推进算法
16. 最高标号预流推进 HLPP 算法
17. Primal-Dual 原始对偶算法(最小费用流)18. Kosaraju 算法(有向图强连通分量)
19. Tarjan 算法(有向图强连通分量)
20. Gabow 算法(有向图强连通分量)
21. 匈牙利算法(二分图匹配)
22. Hopcroft－Karp 算法(二分图匹配)
23. kuhn munkras 算法(二分图最佳匹配)
24. Edmonds’ Blossom-Contraction 算法(一般图匹配)
1. 图遍历
2. 有向图和无向图的强弱连通性
3. 割点/割边
3. AOV 网络和拓扑排序
4. AOE 网络和关键路径
5. 最小代价生成树/次小生成树
6. 最短路径问题/第 K 短路问题
7. 最大网络流问题
8. 最小费用流问题
9. 图着色问题
10. 差分约束系统
11. 欧拉回路
12. 中国邮递员问题
13. 汉密尔顿回路
14. 最佳边割集/最佳点割集/最小边割集/最小点割集/最小路径覆盖/最小点集覆盖
15. 边覆盖集
16. 二分图完美匹配和最大匹配问题
17. 仙人掌图
18. 弦图
19. 稳定婚姻问题
20. 最大团问题
数论
1. 最大公约数
2. 最小公倍数
3. 分解质因数
4. 素数判定
5. 进制转换
6. 高精度计算
7. 整除问题
8. 同余问题
9. 欧拉函数
10. 扩展欧几里得
11. 置换群
12. 母函数
13. 离散变换
14. 康托展开
15. 矩阵
16. 向量
17. 线性方程组
18. 线性规划
几何
1. 凸包 - Gift wrapping
2. 凸包 - Graham scan
3. 线段问题
4. 多边形和多面体相关问题
NP 完全
1. 计算模型
2. P 类与 NP 类问题
3. NP 完全问题
4. NP 完全问题的近似算法
1. 随机存取机 RAM
2. 随机存取存储程序机 RASP
3. 图灵机
4. 非确定性图灵机
5. P 类与 NP 类语言
6. 多项式时间验证
7. 多项式时间变换
8. Cook定理
9. 合取范式的可满足性问题 CNF-SAT
10. 3 元合取范式的可满足性问题 3-SAT
11. 团问题 CLIQUE
12. 顶点覆盖问题 VERTEX-COVER
13. 子集和问题 SUBSET-SUM
14. 哈密顿回路问题 HAM-CYCLE
15. 旅行售货员问题 TSP
16. 顶点覆盖问题的近似算法
17. 旅行售货员问题近似算法
18. 具有三角不等式性质的旅行售货员问题
19. 一般的旅行售货员问题
20. 集合覆盖问题的近似算法
21. 子集和问题的近似算法
22. 子集和问题的指数时间算法
23. 子集和问题的多项式时间近似格式
------------ ------------------------------------------------------------------ ----------------------------------------------------------------- --------------------
LeetCode Problems
# Title Solution Acceptance Difficulty Frequency 0001 Two Sum Go 45.6% Easy
0002 Add Two Numbers Go 33.9% Medium
0003 Longest Substring Without Repeating Characters Go 30.4% Medium
0004 Median of Two Sorted Arrays Go 29.6% Hard
0005 Longest Palindromic Substring
29.4% Medium
0006 ZigZag Conversion
36.3% Medium
0007 Reverse Integer Go 25.8% Easy
0008 String to Integer (atoi)
15.4% Medium
0009 Palindrome Number Go 48.4% Easy
0010 Regular Expression Matching
26.8% Hard
0011 Container With Most Water Go 50.8% Medium
0012 Integer to Roman
55.0% Medium
0013 Roman to Integer Go 55.7% Easy
0014 Longest Common Prefix
35.4% Easy
0015 3Sum Go 26.8% Medium
0016 3Sum Closest Go 46.0% Medium
0017 Letter Combinations of a Phone Number Go 46.8% Medium
0018 4Sum Go 33.6% Medium
0019 Remove Nth Node From End of List Go 35.2% Medium
0020 Valid Parentheses Go 38.9% Easy
0021 Merge Two Sorted Lists Go 53.5% Easy
0022 Generate Parentheses Go 62.6% Medium
0023 Merge k Sorted Lists Go 40.2% Hard
0024 Swap Nodes in Pairs Go 50.3% Medium
0025 Reverse Nodes in k-Group Go 42.0% Hard
0026 Remove Duplicates from Sorted Array Go 45.1% Easy
0027 Remove Element Go 48.2% Easy
0028 Implement strStr() Go 34.5% Easy
0029 Divide Two Integers Go 16.4% Medium
0030 Substring with Concatenation of All Words Go(是否还有更优解) 25.4% Hard
0031 Next Permutation
32.6% Medium
0032 Longest Valid Parentheses
28.4% Hard
0033 Search in Rotated Sorted Array Go 34.5% Medium
0034 Find First and Last Position of Element in Sorted Array Go 36.1% Medium
0035 Search Insert Position Go 42.6% Easy
0036 Valid Sudoku Go 48.7% Medium
0037 Sudoku Solver Go 43.5% Hard
0038 Count and Say
44.6% Easy
0039 Combination Sum Go 56.0% Medium
0040 Combination Sum II Go 48.1% Medium
0041 First Missing Positive Go 32.0% Hard
0042 Trapping Rain Water Go 48.8% Hard
0043 Multiply Strings
33.9% Medium
0044 Wildcard Matching
24.7% Hard
0045 Jump Game II
30.5% Hard
0046 Permutations Go 63.5% Medium
0047 Permutations II Go 46.4% Medium
0048 Rotate Image Go 56.6% Medium
0049 Group Anagrams Go 56.8% Medium
0050 Pow(x, n) Go 30.3% Medium
0051 N-Queens Go 46.6% Hard
0052 N-Queens II Go 57.8% Hard
0053 Maximum Subarray Go 46.5% Easy
0054 Spiral Matrix Go 34.1% Medium
0055 Jump Game Go 34.6% Medium
0056 Merge Intervals Go 39.3% Medium
0057 Insert Interval Go 33.5% Hard
0058 Length of Last Word
32.6% Easy
0059 Spiral Matrix II Go 53.8% Medium
0060 Permutation Sequence Go 38.4% Hard
0061 Rotate List Go 30.0% Medium
0062 Unique Paths Go 54.1% Medium
0063 Unique Paths II Go 34.5% Medium
0064 Minimum Path Sum Go 54.4% Medium
0065 Valid Number
15.3% Hard
0066 Plus One Go 43.0% Easy
0067 Add Binary Go 45.2% Easy
0068 Text Justification
27.7% Hard
0069 Sqrt(x) Go 33.9% Easy
0070 Climbing Stairs Go 47.8% Easy
0071 Simplify Path Go 32.6% Medium
0072 Edit Distance
44.8% Hard
0073 Set Matrix Zeroes
43.1% Medium
0074 Search a 2D Matrix Go 36.5% Medium
0075 Sort Colors Go 47.3% Medium
0076 Minimum Window Substring Go 34.6% Hard
0077 Combinations Go 54.7% Medium
0078 Subsets Go 61.9% Medium
0079 Word Search Go 35.6% Medium
0080 Remove Duplicates from Sorted Array II Go 43.9% Medium
0081 Search in Rotated Sorted Array II Go 33.0% Medium
0082 Remove Duplicates from Sorted List II Go 36.8% Medium
0083 Remove Duplicates from Sorted List Go 45.4% Easy
0084 Largest Rectangle in Histogram Go 35.1% Hard
0085 Maximal Rectangle
37.7% Hard
0086 Partition List Go 41.4% Medium
0087 Scramble String
33.7% Hard
0088 Merge Sorted Array Go 39.4% Easy
0089 Gray Code Go 49.1% Medium
0090 Subsets II Go 47.1% Medium
0091 Decode Ways Go 24.6% Medium
0092 Reverse Linked List II Go 38.8% Medium
0093 Restore IP Addresses Go 35.6% Medium
0094 Binary Tree Inorder Traversal Go 63.3% Medium
0095 Unique Binary Search Trees II Go 40.6% Medium
0096 Unique Binary Search Trees Go 52.9% Medium
0097 Interleaving String
31.5% Hard
0098 Validate Binary Search Tree Go 27.8% Medium
0099 Recover Binary Search Tree Go 39.6% Hard
0100 Same Tree Go 53.4% Easy
0101 Symmetric Tree Go 46.8% Easy
0102 Binary Tree Level Order Traversal Go 54.5% Medium
0103 Binary Tree Zigzag Level Order Traversal Go 48.3% Medium
0104 Maximum Depth of Binary Tree Go 66.0% Easy
0105 Construct Binary Tree from Preorder and Inorder Traversal Go 48.8% Medium
0106 Construct Binary Tree from Inorder and Postorder Traversal Go 47.1% Medium
0107 Binary Tree Level Order Traversal II Go 53.5% Easy
0108 Convert Sorted Array to Binary Search Tree Go 57.9% Easy
0109 Convert Sorted List to Binary Search Tree Go 47.6% Medium
0110 Balanced Binary Tree Go 43.5% Easy
0111 Minimum Depth of Binary Tree Go 37.4% Easy
0112 Path Sum Go 41.1% Easy
0113 Path Sum II Go 46.6% Medium
0114 Flatten Binary Tree to Linked List Go 49.2% Medium
0115 Distinct Subsequences
38.2% Hard
0116 Populating Next Right Pointers in Each Node
45.2% Medium
0117 Populating Next Right Pointers in Each Node II
39.1% Medium
0118 Pascal's Triangle
52.4% Easy
0119 Pascal's Triangle II
49.0% Easy
0120 Triangle Go 44.1% Medium
0121 Best Time to Buy and Sell Stock Go 50.4% Easy
0122 Best Time to Buy and Sell Stock II Go 56.9% Easy
0123 Best Time to Buy and Sell Stock III
37.4% Hard
0124 Binary Tree Maximum Path Sum Go 34.3% Hard
0125 Valid Palindrome Go 36.7% Easy
0126 Word Ladder II Go 22.1% Hard
0127 Word Ladder Go 29.5% Medium
0128 Longest Consecutive Sequence Go 45.1% Hard
0129 Sum Root to Leaf Numbers Go 49.0% Medium
0130 Surrounded Regions Go 28.1% Medium
0131 Palindrome Partitioning Go 47.5% Medium
0132 Palindrome Partitioning II
30.2% Hard
0133 Clone Graph
34.7% Medium
0134 Gas Station
38.5% Medium
0135 Candy
31.6% Hard
0136 Single Number Go 65.5% Easy
0137 Single Number II Go 52.4% Medium
0138 Copy List with Random Pointer
36.3% Medium
0139 Word Break
40.0% Medium
0140 Word Break II
32.6% Hard
0141 Linked List Cycle Go 41.1% Easy
0142 Linked List Cycle II Go 37.3% Medium
0143 Reorder List Go 37.0% Medium
0144 Binary Tree Preorder Traversal Go 55.6% Medium
0145 Binary Tree Postorder Traversal Go 54.9% Hard
0146 LRU Cache
33.1% Medium
0147 Insertion Sort List Go 41.1% Medium
0148 Sort List Go 42.3% Medium
0149 Max Points on a Line
16.9% Hard
0150 Evaluate Reverse Polish Notation Go 36.3% Medium
0151 Reverse Words in a String Go 21.9% Medium
0152 Maximum Product Subarray Go 31.7% Medium
0153 Find Minimum in Rotated Sorted Array Go 45.1% Medium
0154 Find Minimum in Rotated Sorted Array II Go 41.6% Hard
0155 Min Stack Go 44.4% Easy
0156 Binary Tree Upside Down
55.0% Medium
0157 Read N Characters Given Read4
34.2% Easy
0158 Read N Characters Given Read4 II - Call multiple times
33.7% Hard
0159 Longest Substring with At Most Two Distinct Characters
49.4% Medium
0160 Intersection of Two Linked Lists Go 40.5% Easy
0161 One Edit Distance
32.3% Medium
0162 Find Peak Element Go 43.3% Medium
0163 Missing Ranges
24.3% Medium
0164 Maximum Gap Go 35.4% Hard
0165 Compare Version Numbers
27.4% Medium
0166 Fraction to Recurring Decimal
21.6% Medium
0167 Two Sum II - Input array is sorted Go 54.0% Easy
0168 Excel Sheet Column Title Go 31.0% Easy
0169 Majority Element Go 58.7% Easy
0170 Two Sum III - Data structure design
33.5% Easy
0171 Excel Sheet Column Number Go 54.6% Easy
0172 Factorial Trailing Zeroes Go 37.8% Easy
0173 Binary Search Tree Iterator Go 56.5% Medium
0174 Dungeon Game Go 32.3% Hard
0175 Combine Two Tables
60.7% Easy
0176 Second Highest Salary
31.6% Easy
0177 Nth Highest Salary
31.3% Medium
0178 Rank Scores
45.8% Medium
0179 Largest Number Go 28.7% Medium
0180 Consecutive Numbers
39.7% Medium
0181 Employees Earning More Than Their Managers
56.8% Easy
0182 Duplicate Emails
62.0% Easy
0183 Customers Who Never Order
53.4% Easy
0184 Department Highest Salary
36.6% Medium
0185 Department Top Three Salaries
34.5% Hard
0186 Reverse Words in a String II
43.3% Medium
0187 Repeated DNA Sequences Go 38.9% Medium
0188 Best Time to Buy and Sell Stock IV
28.0% Hard
0189 Rotate Array
34.7% Easy
0190 Reverse Bits Go 39.7% Easy
0191 Number of 1 Bits Go 49.8% Easy
0192 Word Frequency
25.8% Medium
0193 Valid Phone Numbers
25.3% Easy
0194 Transpose File
24.1% Medium
0195 Tenth Line
33.0% Easy
0196 Delete Duplicate Emails
41.0% Easy
0197 Rising Temperature
38.4% Easy
0198 House Robber Go 42.0% Easy
0199 Binary Tree Right Side View Go 54.0% Medium
0200 Number of Islands Go 46.8% Medium
0201 Bitwise AND of Numbers Range Go 39.3% Medium
0202 Happy Number Go 50.4% Easy
0203 Remove Linked List Elements Go 38.6% Easy
0204 Count Primes Go 31.5% Easy
0205 Isomorphic Strings Go 39.8% Easy
0206 Reverse Linked List Go 62.5% Easy
0207 Course Schedule Go 43.1% Medium
0208 Implement Trie (Prefix Tree) Go 49.3% Medium
0209 Minimum Size Subarray Sum Go 38.1% Medium
0210 Course Schedule II Go 40.7% Medium
0211 Add and Search Word - Data structure design Go 38.1% Medium
0212 Word Search II Go 34.8% Hard
0213 House Robber II Go 36.5% Medium
0214 Shortest Palindrome
29.8% Hard
0215 Kth Largest Element in an Array Go 55.3% Medium
0216 Combination Sum III Go 56.5% Medium
0217 Contains Duplicate Go 56.0% Easy
0218 The Skyline Problem Go 34.5% Hard
0219 Contains Duplicate II Go 37.7% Easy
0220 Contains Duplicate III Go 20.9% Medium
0221 Maximal Square
37.7% Medium
0222 Count Complete Tree Nodes Go 46.7% Medium
0223 Rectangle Area Go 37.8% Medium
0224 Basic Calculator Go 36.8% Hard
0225 Implement Stack using Queues Go 45.1% Easy
0226 Invert Binary Tree Go 64.9% Easy
0227 Basic Calculator II
36.9% Medium
0228 Summary Ranges
39.5% Medium
0229 Majority Element II Go 35.6% Medium
0230 Kth Smallest Element in a BST Go 60.2% Medium
0231 Power of Two Go 43.7% Easy
0232 Implement Queue using Stacks Go 49.5% Easy
0233 Number of Digit One
31.3% Hard
0234 Palindrome Linked List Go 39.2% Easy
0235 Lowest Common Ancestor of a Binary Search Tree Go 49.9% Easy
0236 Lowest Common Ancestor of a Binary Tree Go 45.6% Medium
0237 Delete Node in a Linked List Go 63.7% Easy
0238 Product of Array Except Self
60.1% Medium
0239 Sliding Window Maximum Go 43.0% Hard
0240 Search a 2D Matrix II Go 43.1% Medium
0241 Different Ways to Add Parentheses
55.2% Medium
0242 Valid Anagram Go 56.8% Easy
0243 Shortest Word Distance
61.0% Easy
0244 Shortest Word Distance II
52.3% Medium
0245 Shortest Word Distance III
55.3% Medium
0246 Strobogrammatic Number
45.0% Easy
0247 Strobogrammatic Number II
47.6% Medium
0248 Strobogrammatic Number III
39.6% Hard
0249 Group Shifted Strings
55.0% Medium
0250 Count Univalue Subtrees
51.9% Medium
0251 Flatten 2D Vector
45.7% Medium
0252 Meeting Rooms
54.6% Easy
0253 Meeting Rooms II
45.7% Medium
0254 Factor Combinations
46.7% Medium
0255 Verify Preorder Sequence in Binary Search Tree
45.7% Medium
0256 Paint House
52.1% Easy
0257 Binary Tree Paths Go 51.4% Easy
0258 Add Digits Go 57.6% Easy
0259 3Sum Smaller
47.6% Medium
0260 Single Number III Go 64.3% Medium
0261 Graph Valid Tree
42.2% Medium
0262 Trips and Users
32.6% Hard
0263 Ugly Number Go 41.6% Easy
0264 Ugly Number II
42.0% Medium
0265 Paint House II
44.6% Hard
0266 Palindrome Permutation
61.9% Easy
0267 Palindrome Permutation II
36.4% Medium
0268 Missing Number Go 51.7% Easy
0269 Alien Dictionary
33.3% Hard
0270 Closest Binary Search Tree Value
48.1% Easy
0271 Encode and Decode Strings
31.5% Medium
0272 Closest Binary Search Tree Value II
50.5% Hard
0273 Integer to English Words
27.0% Hard
0274 H-Index Go 35.9% Medium
0275 H-Index II Go 35.9% Medium
0276 Paint Fence
38.3% Easy
0277 Find the Celebrity
41.8% Medium
0278 First Bad Version
35.7% Easy
0279 Perfect Squares
47.3% Medium
0280 Wiggle Sort
63.8% Medium
0281 Zigzag Iterator
58.4% Medium
0282 Expression Add Operators
35.5% Hard
0283 Move Zeroes Go 57.8% Easy
0284 Peeking Iterator
45.6% Medium
0285 Inorder Successor in BST
40.3% Medium
0286 Walls and Gates
54.5% Medium
0287 Find the Duplicate Number Go 55.5% Medium
0288 Unique Word Abbreviation
21.9% Medium
0289 Game of Life
54.4% Medium
0290 Word Pattern Go 37.0% Easy
0291 Word Pattern II
43.4% Hard
0292 Nim Game
54.9% Easy
0293 Flip Game
60.6% Easy
0294 Flip Game II
50.0% Medium
0295 Find Median from Data Stream
44.3% Hard
0296 Best Meeting Point
57.5% Hard
0297 Serialize and Deserialize Binary Tree
47.4% Hard
0298 Binary Tree Longest Consecutive Sequence
47.1% Medium
0299 Bulls and Cows
42.4% Easy
0300 Longest Increasing Subsequence Go 42.6% Medium
0301 Remove Invalid Parentheses
43.3% Hard
0302 Smallest Rectangle Enclosing Black Pixels
51.6% Hard
0303 Range Sum Query - Immutable Go 44.7% Easy
0304 Range Sum Query 2D - Immutable
38.5% Medium
0305 Number of Islands II
40.1% Hard
0306 Additive Number Go 29.3% Medium
0307 Range Sum Query - Mutable Go 34.6% Medium
0308 Range Sum Query 2D - Mutable
35.6% Hard
0309 Best Time to Buy and Sell Stock with Cooldown Go 47.4% Medium
0310 Minimum Height Trees
32.3% Medium
0311 Sparse Matrix Multiplication
61.8% Medium
0312 Burst Balloons
51.7% Hard
0313 Super Ugly Number
45.0% Medium
0314 Binary Tree Vertical Order Traversal
45.2% Medium
0315 Count of Smaller Numbers After Self Go 41.5% Hard
0316 Remove Duplicate Letters
35.8% Hard
0317 Shortest Distance from All Buildings
41.4% Hard
0318 Maximum Product of Word Lengths Go 51.2% Medium
0319 Bulb Switcher
45.4% Medium
0320 Generalized Abbreviation
52.0% Medium
0321 Create Maximum Number
27.0% Hard
0322 Coin Change Go 35.4% Medium
0323 Number of Connected Components in an Undirected Graph
56.0% Medium
0324 Wiggle Sort II Go 29.9% Medium
0325 Maximum Size Subarray Sum Equals k
46.8% Medium
0326 Power of Three Go 42.1% Easy
0327 Count of Range Sum Go 35.1% Hard
0328 Odd Even Linked List Go 55.7% Medium
0329 Longest Increasing Path in a Matrix Go 43.4% Hard
0330 Patching Array
34.5% Hard
0331 Verify Preorder Serialization of a Binary Tree Go 40.4% Medium
0332 Reconstruct Itinerary
36.7% Medium
0333 Largest BST Subtree
35.8% Medium
0334 Increasing Triplet Subsequence
40.0% Medium
0335 Self Crossing
28.0% Hard
0336 Palindrome Pairs
33.7% Hard
0337 House Robber III Go 50.6% Medium
0338 Counting Bits Go 69.5% Medium
0339 Nested List Weight Sum
73.9% Easy
0340 Longest Substring with At Most K Distinct Characters
44.0% Hard
0341 Flatten Nested List Iterator
52.9% Medium
0342 Power of Four Go 41.7% Easy
0343 Integer Break Go 50.4% Medium
0344 Reverse String Go 68.5% Easy
0345 Reverse Vowels of a String Go 44.2% Easy
0346 Moving Average from Data Stream
70.9% Easy
0347 Top K Frequent Elements Go 61.2% Medium
0348 Design Tic-Tac-Toe
54.3% Medium
0349 Intersection of Two Arrays Go 62.5% Easy
0350 Intersection of Two Arrays II Go 51.3% Easy
0351 Android Unlock Patterns
48.4% Medium
0352 Data Stream as Disjoint Intervals
47.3% Hard
0353 Design Snake Game
34.1% Medium
0354 Russian Doll Envelopes Go 35.6% Hard
0355 Design Twitter
30.3% Medium
0356 Line Reflection
31.8% Medium
0357 Count Numbers with Unique Digits Go 48.4% Medium
0358 Rearrange String k Distance Apart
34.9% Hard
0359 Logger Rate Limiter
70.8% Easy
0360 Sort Transformed Array
48.8% Medium
0361 Bomb Enemy
46.0% Medium
0362 Design Hit Counter
63.6% Medium
0363 Max Sum of Rectangle No Larger Than K
37.3% Hard
0364 Nested List Weight Sum II
62.7% Medium
0365 Water and Jug Problem
30.6% Medium
0366 Find Leaves of Binary Tree
70.6% Medium
0367 Valid Perfect Square Go 41.7% Easy
0368 Largest Divisible Subset
38.1% Medium
0369 Plus One Linked List
58.2% Medium
0370 Range Addition
62.8% Medium
0371 Sum of Two Integers Go 50.7% Medium
0372 Super Pow Go 36.4% Medium
0373 Find K Pairs with Smallest Sums Go 36.7% Medium
0374 Guess Number Higher or Lower
43.0% Easy
0375 Guess Number Higher or Lower II
40.3% Medium
0376 Wiggle Subsequence
39.6% Medium
0377 Combination Sum IV
45.3% Medium
0378 Kth Smallest Element in a Sorted Matrix Go 54.3% Medium
0379 Design Phone Directory
46.8% Medium
0380 Insert Delete GetRandom O(1)
47.5% Medium
0381 Insert Delete GetRandom O(1) - Duplicates allowed
34.1% Hard
0382 Linked List Random Node
52.1% Medium
0383 Ransom Note
53.1% Easy
0384 Shuffle an Array
52.8% Medium
0385 Mini Parser Go 33.8% Medium
0386 Lexicographical Numbers Go 51.6% Medium
0387 First Unique Character in a String Go 53.3% Easy
0388 Longest Absolute File Path
41.7% Medium
0389 Find the Difference Go 55.3% Easy
0390 Elimination Game
44.5% Medium
0391 Perfect Rectangle
30.4% Hard
0392 Is Subsequence Go 49.2% Easy
0393 UTF-8 Validation Go 37.5% Medium
0394 Decode String Go 49.9% Medium
0395 Longest Substring with At Least K Repeating Characters
41.4% Medium
0396 Rotate Function
36.3% Medium
0397 Integer Replacement Go 32.9% Medium
0398 Random Pick Index
55.9% Medium
0399 Evaluate Division Go 51.6% Medium
0400 Nth Digit
31.7% Medium
0401 Binary Watch Go 47.5% Easy
0402 Remove K Digits Go 28.4% Medium
0403 Frog Jump
39.7% Hard
0404 Sum of Left Leaves Go 50.9% Easy
0405 Convert a Number to Hexadecimal Go 43.9% Easy
0406 Queue Reconstruction by Height
66.8% Medium
0407 Trapping Rain Water II
42.4% Hard
0408 Valid Word Abbreviation
30.6% Easy
0409 Longest Palindrome Go 50.3% Easy
0410 Split Array Largest Sum Go 44.5% Hard
0411 Minimum Unique Word Abbreviation
36.3% Hard
0412 Fizz Buzz Go 62.3% Easy
0413 Arithmetic Slices
57.9% Medium
0414 Third Maximum Number Go 30.5% Easy
0415 Add Strings
47.5% Easy
0416 Partition Equal Subset Sum Go 43.7% Medium
0417 Pacific Atlantic Water Flow
41.1% Medium
0418 Sentence Screen Fitting
32.6% Medium
0419 Battleships in a Board
70.0% Medium
0420 Strong Password Checker
14.1% Hard
0421 Maximum XOR of Two Numbers in an Array Go 53.5% Medium
0422 Valid Word Square
37.7% Easy
0423 Reconstruct Original Digits from English
46.9% Medium
0424 Longest Repeating Character Replacement Go 47.0% Medium
0425 Word Squares
47.6% Hard
0426 Convert Binary Search Tree to Sorted Doubly Linked List
59.1% Medium
0427 Construct Quad Tree
61.4% Medium
0428 Serialize and Deserialize N-ary Tree
59.4% Hard
0429 N-ary Tree Level Order Traversal
65.0% Medium
0430 Flatten a Multilevel Doubly Linked List
55.1% Medium
0431 Encode N-ary Tree to Binary Tree
70.8% Hard
0432 All O`one Data Structure
32.4% Hard
0433 Minimum Genetic Mutation Go 41.8% Medium
0434 Number of Segments in a String
37.7% Easy
0435 Non-overlapping Intervals Go 42.9% Medium
0436 Find Right Interval Go 45.4% Medium
0437 Path Sum III Go 46.5% Medium
0438 Find All Anagrams in a String Go 43.3% Medium
0439 Ternary Expression Parser
55.9% Medium
0440 K-th Smallest in Lexicographical Order
29.1% Hard
0441 Arranging Coins Go 41.8% Easy
0442 Find All Duplicates in an Array
67.7% Medium
0443 String Compression
41.3% Easy
0444 Sequence Reconstruction
22.2% Medium
0445 Add Two Numbers II Go 54.5% Medium
0446 Arithmetic Slices II - Subsequence
32.7% Hard
0447 Number of Boomerangs Go 51.8% Easy
0448 Find All Numbers Disappeared in an Array Go 55.9% Easy
0449 Serialize and Deserialize BST
52.0% Medium
0450 Delete Node in a BST
43.1% Medium
0451 Sort Characters By Frequency Go 63.0% Medium
0452 Minimum Number of Arrows to Burst Balloons
49.6% Medium
0453 Minimum Moves to Equal Array Elements Go 50.2% Easy
0454 4Sum II Go 53.1% Medium
0455 Assign Cookies Go 49.9% Easy
0456 132 Pattern Go 28.9% Medium
0457 Circular Array Loop Go 29.4% Medium
0458 Poor Pigs
47.4% Hard
0459 Repeated Substring Pattern
42.2% Easy
0460 LFU Cache
34.2% Hard
0461 Hamming Distance Go 72.8% Easy
0462 Minimum Moves to Equal Array Elements II
53.8% Medium
0463 Island Perimeter Go 65.7% Easy
0464 Can I Win
28.8% Medium
0465 Optimal Account Balancing
46.8% Hard
0466 Count The Repetitions
28.2% Hard
0467 Unique Substrings in Wraparound String
35.6% Medium
0468 Validate IP Address
24.0% Medium
0469 Convex Polygon
37.0% Medium
0470 Implement Rand10() Using Rand7() Go 46.3% Medium
0471 Encode String with Shortest Length
47.1% Hard
0472 Concatenated Words
43.6% Hard
0473 Matchsticks to Square
37.7% Medium
0474 Ones and Zeroes Go 42.8% Medium
0475 Heaters Go 33.1% Easy
0476 Number Complement Go 64.8% Easy
0477 Total Hamming Distance Go 50.5% Medium
0478 Generate Random Point in a Circle
38.5% Medium
0479 Largest Palindrome Product
29.0% Hard
0480 Sliding Window Median Go 37.2% Hard
0481 Magical String
47.5% Medium
0482 License Key Formatting
43.1% Easy
0483 Smallest Good Base Go 35.7% Hard
0484 Find Permutation
60.5% Medium
0485 Max Consecutive Ones Go 54.7% Easy
0486 Predict the Winner
47.9% Medium
0487 Max Consecutive Ones II
48.5% Medium
0488 Zuma Game
39.8% Hard
0489 Robot Room Cleaner
69.7% Hard
0490 The Maze
51.4% Medium
0491 Increasing Subsequences Go 46.1% Medium
0492 Construct the Rectangle
49.6% Easy
0493 Reverse Pairs Go 25.2% Hard
0494 Target Sum Go 46.3% Medium
0495 Teemo Attacking
53.6% Medium
0496 Next Greater Element I Go 63.8% Easy
0497 Random Point in Non-overlapping Rectangles Go 37.8% Medium
0498 Diagonal Traverse Go 48.2% Medium
0499 The Maze III
41.0% Hard
0500 Keyboard Row Go 64.7% Easy
0501 Find Mode in Binary Search Tree
42.3% Easy
0502 IPO
40.4% Hard
0503 Next Greater Element II Go 56.5% Medium
0504 Base 7
46.2% Easy
0505 The Maze II
47.7% Medium
0506 Relative Ranks
50.5% Easy
0507 Perfect Number Go 35.5% Easy
0508 Most Frequent Subtree Sum Go 57.9% Medium
0509 Fibonacci Number Go 67.2% Easy
0510 Inorder Successor in BST II
58.0% Medium
0511 Game Play Analysis I
80.8% Easy
0512 Game Play Analysis II
55.5% Easy
0513 Find Bottom Left Tree Value Go 61.5% Medium
0514 Freedom Trail
43.0% Hard
0515 Find Largest Value in Each Tree Row Go 61.1% Medium
0516 Longest Palindromic Subsequence
53.2% Medium
0517 Super Washing Machines
38.3% Hard
0518 Coin Change 2
50.2% Medium
0519 Random Flip Matrix
36.7% Medium
0520 Detect Capital
54.4% Easy
0521 Longest Uncommon Subsequence I
57.6% Easy
0522 Longest Uncommon Subsequence II
34.0% Medium
0523 Continuous Subarray Sum
24.6% Medium
0524 Longest Word in Dictionary through Deleting Go 48.4% Medium
0525 Contiguous Array
42.8% Medium
0526 Beautiful Arrangement Go 57.8% Medium
0527 Word Abbreviation
54.2% Hard
0528 Random Pick with Weight Go 43.9% Medium
0529 Minesweeper Go 59.1% Medium
0530 Minimum Absolute Difference in BST
53.7% Easy
0531 Lonely Pixel I
59.0% Medium
0532 K-diff Pairs in an Array Go 31.5% Easy
0533 Lonely Pixel II
47.9% Medium
0534 Game Play Analysis III
75.9% Medium
0535 Encode and Decode TinyURL
79.9% Medium
0536 Construct Binary Tree from String
48.3% Medium
0537 Complex Number Multiplication Go 67.4% Medium
0538 Convert BST to Greater Tree
55.3% Easy
0539 Minimum Time Difference
51.5% Medium
0540 Single Element in a Sorted Array
57.9% Medium
0541 Reverse String II Go 48.4% Easy
0542 01 Matrix Go 39.8% Medium
0543 Diameter of Binary Tree
48.4% Easy
0544 Output Contest Matches
75.2% Medium
0545 Boundary of Binary Tree
38.9% Medium
0546 Remove Boxes
42.7% Hard
0547 Friend Circles Go 58.5% Medium
0548 Split Array with Equal Sum
46.4% Medium
0549 Binary Tree Longest Consecutive Sequence II
47.0% Medium
0550 Game Play Analysis IV
45.2% Medium
0551 Student Attendance Record I
46.0% Easy
0552 Student Attendance Record II
36.7% Hard
0553 Optimal Division
56.7% Medium
0554 Brick Wall
50.0% Medium
0555 Split Concatenated Strings
42.2% Medium
0556 Next Greater Element III
31.7% Medium
0557 Reverse Words in a String III Go 69.8% Easy
0558 Logical OR of Two Binary Grids Represented as Quad-Trees
44.6% Medium
0559 Maximum Depth of N-ary Tree
68.6% Easy
0560 Subarray Sum Equals K
43.8% Medium
0561 Array Partition I Go 72.0% Easy
0562 Longest Line of Consecutive One in Matrix
45.8% Medium
0563 Binary Tree Tilt Go 48.7% Easy
0564 Find the Closest Palindrome
19.7% Hard
0565 Array Nesting
55.5% Medium
0566 Reshape the Matrix Go 60.5% Easy
0567 Permutation in String Go 44.4% Medium
0568 Maximum Vacation Days
40.8% Hard
0569 Median Employee Salary
57.6% Hard
0570 Managers with at Least 5 Direct Reports
66.0% Medium
0571 Find Median Given Frequency of Numbers
44.7% Hard
0572 Subtree of Another Tree Go 44.1% Easy
0573 Squirrel Simulation
55.6% Medium
0574 Winning Candidate
47.5% Medium
0575 Distribute Candies Go 61.4% Easy
0576 Out of Boundary Paths
35.1% Medium
0577 Employee Bonus
68.1% Easy
0578 Get Highest Answer Rate Question
39.3% Medium
0579 Find Cumulative Salary of an Employee
37.0% Hard
0580 Count Student Number in Departments
48.7% Medium
0581 Shortest Unsorted Continuous Subarray
31.1% Easy
0582 Kill Process
60.8% Medium
0583 Delete Operation for Two Strings
48.6% Medium
0584 Find Customer Referee
72.2% Easy
0585 Investments in 2016
54.7% Medium
0586 Customer Placing the Largest Number of Orders
72.9% Easy
0587 Erect the Fence
35.9% Hard
0588 Design In-Memory File System
45.9% Hard
0589 N-ary Tree Preorder Traversal
72.0% Easy
0590 N-ary Tree Postorder Traversal
72.1% Easy
0591 Tag Validator
34.3% Hard
0592 Fraction Addition and Subtraction
49.0% Medium
0593 Valid Square
43.1% Medium
0594 Longest Harmonious Subsequence Go 46.6% Easy
0595 Big Countries
77.3% Easy
0596 Classes More Than 5 Students
38.0% Easy
0597 Friend Requests I: Overall Acceptance Rate
40.9% Easy
0598 Range Addition II Go 49.6% Easy
0599 Minimum Index Sum of Two Lists Go 50.7% Easy
0600 Non-negative Integers without Consecutive Ones
34.1% Hard
0601 Human Traffic of Stadium
41.6% Hard
0602 Friend Requests II: Who Has the Most Friends
53.3% Medium
0603 Consecutive Available Seats
63.9% Easy
0604 Design Compressed String Iterator
37.5% Easy
0605 Can Place Flowers
31.6% Easy
0606 Construct String from Binary Tree
54.1% Easy
0607 Sales Person
62.9% Easy
0608 Tree Node
67.0% Medium
0609 Find Duplicate File in System
59.5% Medium
0610 Triangle Judgement
65.9% Easy
0611 Valid Triangle Number
48.4% Medium
0612 Shortest Distance in a Plane
59.5% Medium
0613 Shortest Distance in a Line
77.5% Easy
0614 Second Degree Follower
30.2% Medium
0615 Average Salary: Departments VS Company
46.8% Hard
0616 Add Bold Tag in String
43.0% Medium
0617 Merge Two Binary Trees
74.1% Easy
0618 Students Report By Geography
54.8% Hard
0619 Biggest Single Number
43.1% Easy
0620 Not Boring Movies
67.5% Easy
0621 Task Scheduler
50.0% Medium
0622 Design Circular Queue
43.7% Medium
0623 Add One Row to Tree
49.7% Medium
0624 Maximum Distance in Arrays
38.9% Easy
0625 Minimum Factorization
32.8% Medium
0626 Exchange Seats
62.2% Medium
0627 Swap Salary
75.2% Easy
0628 Maximum Product of Three Numbers Go 47.1% Easy
0629 K Inverse Pairs Array
31.1% Hard
0630 Course Schedule III
33.5% Hard
0631 Design Excel Sum Formula
31.5% Hard
0632 Smallest Range Covering Elements from K Lists Go 52.4% Hard
0633 Sum of Square Numbers Go 32.2% Easy
0634 Find the Derangement of An Array
40.1% Medium
0635 Design Log Storage System
58.6% Medium
0636 Exclusive Time of Functions Go 52.0% Medium
0637 Average of Levels in Binary Tree Go 63.0% Easy
0638 Shopping Offers Go 51.5% Medium
0639 Decode Ways II
26.6% Hard
0640 Solve the Equation
42.0% Medium
0641 Design Circular Deque
52.7% Medium
0642 Design Search Autocomplete System
44.6% Hard
0643 Maximum Average Subarray I
41.5% Easy
0644 Maximum Average Subarray II
32.0% Hard
0645 Set Mismatch Go 42.1% Easy
0646 Maximum Length of Pair Chain
51.8% Medium
0647 Palindromic Substrings
60.6% Medium
0648 Replace Words Go 56.5% Medium
0649 Dota2 Senate
39.2% Medium
0650 2 Keys Keyboard
49.2% Medium
0651 4 Keys Keyboard
52.4% Medium
0652 Find Duplicate Subtrees
50.1% Medium
0653 Two Sum IV - Input is a BST Go 55.5% Easy
0654 Maximum Binary Tree
79.9% Medium
0655 Print Binary Tree
55.0% Medium
0656 Coin Path
29.0% Hard
0657 Robot Return to Origin
73.5% Easy
0658 Find K Closest Elements Go 40.9% Medium
0659 Split Array into Consecutive Subsequences
43.7% Medium
0660 Remove 9
53.3% Hard
0661 Image Smoother Go 51.5% Easy
0662 Maximum Width of Binary Tree Go 41.1% Medium
0663 Equal Tree Partition
39.5% Medium
0664 Strange Printer
40.2% Hard
0665 Non-decreasing Array
19.5% Easy
0666 Path Sum IV
54.7% Medium
0667 Beautiful Arrangement II
54.2% Medium
0668 Kth Smallest Number in Multiplication Table Go 45.6% Hard
0669 Trim a Binary Search Tree
63.0% Easy
0670 Maximum Swap
43.6% Medium
0671 Second Minimum Node In a Binary Tree
42.7% Easy
0672 Bulb Switcher II
50.9% Medium
0673 Number of Longest Increasing Subsequence
35.7% Medium
0674 Longest Continuous Increasing Subsequence
45.9% Easy
0675 Cut Off Trees for Golf Event
34.6% Hard
0676 Implement Magic Dictionary Go 54.5% Medium
0677 Map Sum Pairs
53.5% Medium
0678 Valid Parenthesis String
31.0% Medium
0679 24 Game
46.4% Hard
0680 Valid Palindrome II
36.6% Easy
0681 Next Closest Time
45.0% Medium
0682 Baseball Game Go 63.7% Easy
0683 K Empty Slots
35.7% Hard
0684 Redundant Connection Go 57.3% Medium
0685 Redundant Connection II Go 32.4% Hard
0686 Repeated String Match
32.3% Easy
0687 Longest Univalue Path
36.2% Easy
0688 Knight Probability in Chessboard
48.9% Medium
0689 Maximum Sum of 3 Non-Overlapping Subarrays
46.3% Hard
0690 Employee Importance
57.3% Easy
0691 Stickers to Spell Word
43.0% Hard
0692 Top K Frequent Words
51.8% Medium
0693 Binary Number with Alternating Bits Go 59.4% Easy
0694 Number of Distinct Islands
56.0% Medium
0695 Max Area of Island Go 62.7% Medium
0696 Count Binary Substrings
56.0% Easy
0697 Degree of an Array Go 53.8% Easy
0698 Partition to K Equal Sum Subsets
44.9% Medium
0699 Falling Squares Go 41.8% Hard
0700 Search in a Binary Search Tree
73.1% Easy
0701 Insert into a Binary Search Tree
77.8% Medium
0702 Search in a Sorted Array of Unknown Size
66.7% Medium
0703 Kth Largest Element in a Stream
49.7% Easy
0704 Binary Search Go 52.1% Easy
0705 Design HashSet Go 64.3% Easy
0706 Design HashMap Go 61.3% Easy
0707 Design Linked List Go 24.5% Medium
0708 Insert into a Sorted Circular Linked List
31.6% Medium
0709 To Lower Case
79.3% Easy
0710 Random Pick with Blacklist Go 32.4% Hard
0711 Number of Distinct Islands II
47.3% Hard
0712 Minimum ASCII Delete Sum for Two Strings
58.5% Medium
0713 Subarray Product Less Than K Go 39.1% Medium
0714 Best Time to Buy and Sell Stock with Transaction Fee Go 54.7% Medium
0715 Range Module Go 38.5% Hard
0716 Max Stack
42.6% Easy
0717 1-bit and 2-bit Characters Go 48.8% Easy
0718 Maximum Length of Repeated Subarray Go 49.3% Medium
0719 Find K-th Smallest Pair Distance Go 31.5% Hard
0720 Longest Word in Dictionary Go 48.2% Easy
0721 Accounts Merge Go 48.7% Medium
0722 Remove Comments
34.6% Medium
0723 Candy Crush
69.3% Medium
0724 Find Pivot Index
44.0% Easy
0725 Split Linked List in Parts Go 52.1% Medium
0726 Number of Atoms Go 48.9% Hard
0727 Minimum Window Subsequence
41.8% Hard
0728 Self Dividing Numbers
74.3% Easy
0729 My Calendar I Go 51.8% Medium
0730 Count Different Palindromic Subsequences
41.7% Hard
0731 My Calendar II
49.1% Medium
0732 My Calendar III Go 59.9% Hard
0733 Flood Fill Go 55.3% Easy
0734 Sentence Similarity
42.1% Easy
0735 Asteroid Collision Go 41.1% Medium
0736 Parse Lisp Expression
47.5% Hard
0737 Sentence Similarity II
45.8% Medium
0738 Monotone Increasing Digits
44.3% Medium
0739 Daily Temperatures Go 63.3% Medium
0740 Delete and Earn
48.6% Medium
0741 Cherry Pickup
33.9% Hard
0742 Closest Leaf in a Binary Tree
43.5% Medium
0743 Network Delay Time
44.9% Medium
0744 Find Smallest Letter Greater Than Target Go 45.4% Easy
0745 Prefix and Suffix Search Go 34.1% Hard
0746 Min Cost Climbing Stairs Go 50.3% Easy
0747 Largest Number At Least Twice of Others
42.0% Easy
0748 Shortest Completing Word Go 56.7% Easy
0749 Contain Virus
44.5% Hard
0750 Number Of Corner Rectangles
66.4% Medium
0751 IP to CIDR
61.8% Medium
0752 Open the Lock
51.8% Medium
0753 Cracking the Safe Go 50.5% Hard
0754 Reach a Number
34.7% Medium
0755 Pour Water
43.3% Medium
0756 Pyramid Transition Matrix Go 54.6% Medium
0757 Set Intersection Size At Least Two
40.1% Hard
0758 Bold Words in String
45.9% Easy
0759 Employee Free Time
66.2% Hard
0760 Find Anagram Mappings
81.1% Easy
0761 Special Binary String
54.7% Hard
0762 Prime Number of Set Bits in Binary Representation Go 63.2% Easy
0763 Partition Labels Go 76.0% Medium
0764 Largest Plus Sign
46.0% Medium
0765 Couples Holding Hands Go 54.3% Hard
0766 Toeplitz Matrix Go 65.0% Easy
0767 Reorganize String Go 48.7% Medium
0768 Max Chunks To Make Sorted II
48.7% Hard
0769 Max Chunks To Make Sorted
54.7% Medium
0770 Basic Calculator IV
47.9% Hard
0771 Jewels and Stones Go 86.3% Easy
0772 Basic Calculator III
41.2% Hard
0773 Sliding Puzzle
59.3% Hard
0774 Minimize Max Distance to Gas Station
46.9% Hard
0775 Global and Local Inversions
42.1% Medium
0776 Split BST
55.8% Medium
0777 Swap Adjacent in LR String
34.8% Medium
0778 Swim in Rising Water Go 53.0% Hard
0779 K-th Symbol in Grammar
37.2% Medium
0780 Reaching Points
29.3% Hard
0781 Rabbits in Forest Go 54.5% Medium
0782 Transform to Chessboard
42.8% Hard
0783 Minimum Distance Between BST Nodes
52.6% Easy
0784 Letter Case Permutation Go 64.6% Medium
0785 Is Graph Bipartite?
47.5% Medium
0786 K-th Smallest Prime Fraction Go 41.0% Hard
0787 Cheapest Flights Within K Stops
39.3% Medium
0788 Rotated Digits
57.1% Easy
0789 Escape The Ghosts
57.4% Medium
0790 Domino and Tromino Tiling
39.2% Medium
0791 Custom Sort String
65.7% Medium
0792 Number of Matching Subsequences
47.4% Medium
0793 Preimage Size of Factorial Zeroes Function Go 40.2% Hard
0794 Valid Tic-Tac-Toe State
32.6% Medium
0795 Number of Subarrays with Bounded Maximum
46.3% Medium
0796 Rotate String
49.6% Easy
0797 All Paths From Source to Target
77.9% Medium
0798 Smallest Rotation with Highest Score
44.1% Hard
0799 Champagne Tower
35.7% Medium
0800 Similar RGB Color
61.4% Easy
0801 Minimum Swaps To Make Sequences Increasing
38.9% Medium
0802 Find Eventual Safe States Go 48.9% Medium
0803 Bricks Falling When Hit Go 30.8% Hard
0804 Unique Morse Code Words
77.0% Easy
0805 Split Array With Same Average
26.3% Hard
0806 Number of Lines To Write String
64.9% Easy
0807 Max Increase to Keep City Skyline
83.7% Medium
0808 Soup Servings
39.9% Medium
0809 Expressive Words
47.0% Medium
0810 Chalkboard XOR Game
48.2% Hard
0811 Subdomain Visit Count Go 69.8% Easy
0812 Largest Triangle Area Go 58.3% Easy
0813 Largest Sum of Averages
49.9% Medium
0814 Binary Tree Pruning
74.5% Medium
0815 Bus Routes Go 42.6% Hard
0816 Ambiguous Coordinates
47.2% Medium
0817 Linked List Components Go 57.3% Medium
0818 Race Car
39.0% Hard
0819 Most Common Word Go 44.8% Easy
0820 Short Encoding of Words
50.7% Medium
0821 Shortest Distance to a Character
66.9% Easy
0822 Card Flipping Game
42.9% Medium
0823 Binary Trees With Factors
35.8% Medium
0824 Goat Latin
63.3% Easy
0825 Friends Of Appropriate Ages
42.6% Medium
0826 Most Profit Assigning Work Go 38.5% Medium
0827 Making A Large Island
45.6% Hard
0828 Count Unique Characters of All Substrings of a Given String Go 45.1% Hard
0829 Consecutive Numbers Sum
37.4% Hard
0830 Positions of Large Groups
49.6% Easy
0831 Masking Personal Information
44.1% Medium
0832 Flipping an Image Go 76.2% Easy
0833 Find And Replace in String
50.4% Medium
0834 Sum of Distances in Tree Go 43.7% Hard
0835 Image Overlap
58.5% Medium
0836 Rectangle Overlap Go 48.6% Easy
0837 New 21 Game
34.6% Medium
0838 Push Dominoes Go 48.4% Medium
0839 Similar String Groups Go 38.6% Hard
0840 Magic Squares In Grid
37.3% Easy
0841 Keys and Rooms Go 64.3% Medium
0842 Split Array into Fibonacci Sequence Go 36.3% Medium
0843 Guess the Word
46.1% Hard
0844 Backspace String Compare Go 46.4% Easy
0845 Longest Mountain in Array Go 37.2% Medium
0846 Hand of Straights
54.2% Medium
0847 Shortest Path Visiting All Nodes
52.0% Hard
0848 Shifting Letters
44.6% Medium
0849 Maximize Distance to Closest Person
42.6% Easy
0850 Rectangle Area II Go 47.5% Hard
0851 Loud and Rich Go 51.6% Medium
0852 Peak Index in a Mountain Array Go 71.6% Easy
0853 Car Fleet Go 42.4% Medium
0854 K-Similar Strings
38.2% Hard
0855 Exam Room
43.1% Medium
0856 Score of Parentheses Go 60.5% Medium
0857 Minimum Cost to Hire K Workers
49.6% Hard
0858 Mirror Reflection
53.7% Medium
0859 Buddy Strings
27.4% Easy
0860 Lemonade Change
51.6% Easy
0861 Score After Flipping Matrix
72.8% Medium
0862 Shortest Subarray with Sum at Least K Go 24.6% Hard
0863 All Nodes Distance K in Binary Tree Go 55.3% Medium
0864 Shortest Path to Get All Keys Go 40.1% Hard
0865 Smallest Subtree with all the Deepest Nodes
60.8% Medium
0866 Prime Palindrome
24.9% Medium
0867 Transpose Matrix Go 62.8% Easy
0868 Binary Gap
60.6% Easy
0869 Reordered Power of 2
53.3% Medium
0870 Advantage Shuffle
45.6% Medium
0871 Minimum Number of Refueling Stops
31.4% Hard
0872 Leaf-Similar Trees Go 64.5% Easy
0873 Length of Longest Fibonacci Subsequence
48.0% Medium
0874 Walking Robot Simulation
35.3% Easy
0875 Koko Eating Bananas Go 52.1% Medium
0876 Middle of the Linked List Go 68.4% Easy
0877 Stone Game
64.8% Medium
0878 Nth Magical Number Go 28.4% Hard
0879 Profitable Schemes
39.7% Hard
0880 Decoded String at Index Go 24.3% Medium
0881 Boats to Save People Go 46.8% Medium
0882 Reachable Nodes In Subdivided Graph
41.3% Hard
0883 Projection Area of 3D Shapes
67.7% Easy
0884 Uncommon Words from Two Sentences Go 63.3% Easy
0885 Spiral Matrix III Go 69.3% Medium
0886 Possible Bipartition
44.1% Medium
0887 Super Egg Drop Go 27.0% Hard
0888 Fair Candy Swap Go 58.3% Easy
0889 Construct Binary Tree from Preorder and Postorder Traversal
66.1% Medium
0890 Find and Replace Pattern
73.4% Medium
0891 Sum of Subsequence Widths Go 31.9% Hard
0892 Surface Area of 3D Shapes Go 58.9% Easy
0893 Groups of Special-Equivalent Strings
66.5% Easy
0894 All Possible Full Binary Trees
75.2% Medium
0895 Maximum Frequency Stack Go 60.6% Hard
0896 Monotonic Array Go 57.9% Easy
0897 Increasing Order Search Tree Go 70.7% Easy
0898 Bitwise ORs of Subarrays Go 34.8% Medium
0899 Orderly Queue
52.2% Hard
0900 RLE Iterator
53.5% Medium
0901 Online Stock Span Go 60.1% Medium
0902 Numbers At Most N Given Digit Set
31.5% Hard
0903 Valid Permutations for DI Sequence
49.6% Hard
0904 Fruit Into Baskets Go 42.5% Medium
0905 Sort Array By Parity
74.0% Easy
0906 Super Palindromes
32.7% Hard
0907 Sum of Subarray Minimums Go 32.3% Medium
0908 Smallest Range I
65.8% Easy
0909 Snakes and Ladders
38.4% Medium
0910 Smallest Range II
26.6% Medium
0911 Online Election Go 50.4% Medium
0912 Sort an Array
63.8% Medium
0913 Cat and Mouse
31.3% Hard
0914 X of a Kind in a Deck of Cards Go 34.9% Easy
0915 Partition Array into Disjoint Intervals
45.3% Medium
0916 Word Subsets
47.8% Medium
0917 Reverse Only Letters
57.9% Easy
0918 Maximum Sum Circular Subarray Go 33.6% Medium
0919 Complete Binary Tree Inserter
57.3% Medium
0920 Number of Music Playlists Go 46.5% Hard
0921 Minimum Add to Make Parentheses Valid Go 73.6% Medium
0922 Sort Array By Parity II Go 69.2% Easy
0923 3Sum With Multiplicity Go 35.7% Medium
0924 Minimize Malware Spread Go 42.0% Hard
0925 Long Pressed Name Go 40.6% Easy
0926 Flip String to Monotone Increasing
52.3% Medium
0927 Three Equal Parts Go 33.6% Hard
0928 Minimize Malware Spread II Go 40.5% Hard
0929 Unique Email Addresses
67.4% Easy
0930 Binary Subarrays With Sum Go 43.0% Medium
0931 Minimum Falling Path Sum
62.4% Medium
0932 Beautiful Array
58.3% Medium
0933 Number of Recent Calls Go 71.9% Easy
0934 Shortest Bridge
48.1% Medium
0935 Knight Dialer
45.1% Medium
0936 Stamping The Sequence
42.8% Hard
0937 Reorder Data in Log Files
54.4% Easy
0938 Range Sum of BST
81.3% Easy
0939 Minimum Area Rectangle
51.8% Medium
0940 Distinct Subsequences II
41.4% Hard
0941 Valid Mountain Array
33.3% Easy
0942 DI String Match Go 72.6% Easy
0943 Find the Shortest Superstring
42.8% Hard
0944 Delete Columns to Make Sorted
70.3% Easy
0945 Minimum Increment to Make Array Unique
46.3% Medium
0946 Validate Stack Sequences Go 61.8% Medium
0947 Most Stones Removed with Same Row or Column Go 55.3% Medium
0948 Bag of Tokens
40.8% Medium
0949 Largest Time for Given Digits Go 35.9% Easy
0950 Reveal Cards In Increasing Order
74.6% Medium
0951 Flip Equivalent Binary Trees
65.7% Medium
0952 Largest Component Size by Common Factor Go 30.3% Hard
0953 Verifying an Alien Dictionary Go 54.1% Easy
0954 Array of Doubled Pairs
35.6% Medium
0955 Delete Columns to Make Sorted II
33.2% Medium
0956 Tallest Billboard
39.7% Hard
0957 Prison Cells After N Days
40.7% Medium
0958 Check Completeness of a Binary Tree
52.0% Medium
0959 Regions Cut By Slashes Go 66.1% Medium
0960 Delete Columns to Make Sorted III
53.6% Hard
0961 N-Repeated Element in Size 2N Array Go 73.7% Easy
0962 Maximum Width Ramp
45.3% Medium
0963 Minimum Area Rectangle II
50.8% Medium
0964 Least Operators to Express Number
43.7% Hard
0965 Univalued Binary Tree
67.7% Easy
0966 Vowel Spellchecker
47.2% Medium
0967 Numbers With Same Consecutive Differences
39.4% Medium
0968 Binary Tree Cameras Go 37.5% Hard
0969 Pancake Sorting Go 67.5% Medium
0970 Powerful Integers Go 39.8% Easy
0971 Flip Binary Tree To Match Preorder Traversal
45.6% Medium
0972 Equal Rational Numbers
41.6% Hard
0973 K Closest Points to Origin Go 63.8% Medium
0974 Subarray Sums Divisible by K
48.9% Medium
0975 Odd Even Jump
42.3% Hard
0976 Largest Perimeter Triangle Go 57.6% Easy
0977 Squares of a Sorted Array Go 72.2% Easy
0978 Longest Turbulent Subarray Go 46.6% Medium
0979 Distribute Coins in Binary Tree Go 68.8% Medium
0980 Unique Paths III Go 73.3% Hard
0981 Time Based Key-Value Store Go 53.1% Medium
0982 Triples with Bitwise AND Equal To Zero
55.5% Hard
0983 Minimum Cost For Tickets
60.5% Medium
0984 String Without AAA or BBB Go 37.7% Medium
0985 Sum of Even Numbers After Queries Go 61.3% Easy
0986 Interval List Intersections Go 67.3% Medium
0987 Vertical Order Traversal of a Binary Tree
36.6% Medium
0988 Smallest String Starting From Leaf
46.0% Medium
0989 Add to Array-Form of Integer
44.2% Easy
0990 Satisfiability of Equality Equations Go 44.9% Medium
0991 Broken Calculator
45.5% Medium
0992 Subarrays with K Different Integers Go 48.6% Hard
0993 Cousins in Binary Tree Go 52.0% Easy
0994 Rotting Oranges
47.8% Medium
0995 Minimum Number of K Consecutive Bit Flips Go 46.8% Hard
0996 Number of Squareful Arrays Go 47.9% Hard
0997 Find the Town Judge
50.1% Easy
0998 Maximum Binary Tree II
62.9% Medium
0999 Available Captures for Rook Go 66.7% Easy
1000 Minimum Cost to Merge Stones
39.6% Hard
1001 Grid Illumination
35.9% Hard
1002 Find Common Characters Go 67.7% Easy
1003 Check If Word Is Valid After Substitutions Go 55.3% Medium
1004 Max Consecutive Ones III Go 59.1% Medium
1005 Maximize Sum Of Array After K Negations Go 51.3% Easy
1006 Clumsy Factorial
53.3% Medium
1007 Minimum Domino Rotations For Equal Row
50.0% Medium
1008 Construct Binary Search Tree from Preorder Traversal
78.4% Medium
1009 Complement of Base 10 Integer
59.6% Easy
1010 Pairs of Songs With Total Durations Divisible by 60
47.4% Easy
1011 Capacity To Ship Packages Within D Days Go 58.1% Medium
1012 Numbers With Repeated Digits
37.5% Hard
1013 Partition Array Into Three Parts With Equal Sum
51.8% Easy
1014 Best Sightseeing Pair
52.5% Medium
1015 Smallest Integer Divisible by K
32.1% Medium
1016 Binary String With Substrings Representing 1 To N
58.9% Medium
1017 Convert to Base -2 Go 59.0% Medium
1018 Binary Prefix Divisible By 5
47.7% Easy
1019 Next Greater Node In Linked List Go 57.4% Medium
1020 Number of Enclaves Go 57.7% Medium
1021 Remove Outermost Parentheses Go 77.9% Easy
1022 Sum of Root To Leaf Binary Numbers
67.2% Easy
1023 Camelcase Matching
57.0% Medium
1024 Video Stitching
49.2% Medium
1025 Divisor Game Go 66.3% Easy
1026 Maximum Difference Between Node and Ancestor Go 65.9% Medium
1027 Longest Arithmetic Sequence
53.5% Medium
1028 Recover a Tree From Preorder Traversal Go 69.9% Hard
1029 Two City Scheduling
56.1% Easy
1030 Matrix Cells in Distance Order Go 65.7% Easy
1031 Maximum Sum of Two Non-Overlapping Subarrays
57.8% Medium
1032 Stream of Characters
48.3% Hard
1033 Moving Stones Until Consecutive
41.7% Easy
1034 Coloring A Border
44.7% Medium
1035 Uncrossed Lines
56.1% Medium
1036 Escape a Large Maze
35.4% Hard
1037 Valid Boomerang Go 37.9% Easy
1038 Binary Search Tree to Greater Sum Tree
80.8% Medium
1039 Minimum Score Triangulation of Polygon
49.1% Medium
1040 Moving Stones Until Consecutive II Go 52.9% Medium
1041 Robot Bounded In Circle
49.5% Medium
1042 Flower Planting With No Adjacent
48.5% Easy
1043 Partition Array for Maximum Sum
65.1% Medium
1044 Longest Duplicate Substring
32.0% Hard
1045 Customers Who Bought All Products
67.8% Medium
1046 Last Stone Weight
62.2% Easy
1047 Remove All Adjacent Duplicates In String Go 68.5% Easy
1048 Longest String Chain
54.7% Medium
1049 Last Stone Weight II Go 44.1% Medium
1050 Actors and Directors Who Cooperated At Least Three Times
71.7% Easy
1051 Height Checker Go 71.1% Easy
1052 Grumpy Bookstore Owner Go 55.4% Medium
1053 Previous Permutation With One Swap
48.5% Medium
1054 Distant Barcodes Go 43.2% Medium
1055 Shortest Way to Form String
56.9% Medium
1056 Confusing Number
48.7% Easy
1057 Campus Bikes
57.7% Medium
1058 Minimize Rounding Error to Meet Target
41.7% Medium
1059 All Paths from Source Lead to Destination
44.7% Medium
1060 Missing Element in Sorted Array
54.5% Medium
1061 Lexicographically Smallest Equivalent String
65.2% Medium
1062 Longest Repeating Substring
57.2% Medium
1063 Number of Valid Subarrays
71.1% Hard
1064 Fixed Point
66.5% Easy
1065 Index Pairs of a String
60.6% Easy
1066 Campus Bikes II
54.2% Medium
1067 Digit Count in Range
40.0% Hard
1068 Product Sales Analysis I
83.1% Easy
1069 Product Sales Analysis II
82.9% Easy
1070 Product Sales Analysis III
48.9% Medium
1071 Greatest Common Divisor of Strings
53.0% Easy
1072 Flip Columns For Maximum Number of Equal Rows
60.8% Medium
1073 Adding Two Negabinary Numbers Go 34.0% Medium
1074 Number of Submatrices That Sum to Target Go 59.3% Hard
1075 Project Employees I
64.9% Easy
1076 Project Employees II
53.7% Easy
1077 Project Employees III
75.4% Medium
1078 Occurrences After Bigram Go 64.7% Easy
1079 Letter Tile Possibilities Go 75.4% Medium
1080 Insufficient Nodes in Root to Leaf Paths
49.3% Medium
1081 Smallest Subsequence of Distinct Characters
50.4% Medium
1082 Sales Analysis I
71.7% Easy
1083 Sales Analysis II
50.6% Easy
1084 Sales Analysis III
54.2% Easy
1085 Sum of Digits in the Minimum Number
74.6% Easy
1086 High Five
79.6% Easy
1087 Brace Expansion
62.7% Medium
1088 Confusing Number II
43.9% Hard
1089 Duplicate Zeros Go 53.0% Easy
1090 Largest Values From Labels
58.9% Medium
1091 Shortest Path in Binary Matrix
38.2% Medium
1092 Shortest Common Supersequence
51.6% Hard
1093 Statistics from a Large Sample Go 48.2% Medium
1094 Car Pooling
56.7% Medium
1095 Find in Mountain Array
35.7% Hard
1096 Brace Expansion II
62.1% Hard
1097 Game Play Analysis V
54.4% Hard
1098 Unpopular Books
44.4% Medium
1099 Two Sum Less Than K
60.6% Easy
1100 Find K-Length Substrings With No Repeated Characters
72.7% Medium
1101 The Earliest Moment When Everyone Become Friends
66.2% Medium
1102 Path With Maximum Minimum Value
49.2% Medium
1103 Distribute Candies to People
60.5% Easy
1104 Path In Zigzag Labelled Binary Tree
72.0% Medium
1105 Filling Bookcase Shelves Go 58.1% Medium
1106 Parsing A Boolean Expression
58.5% Hard
1107 New Users Daily Count
45.1% Medium
1108 Defanging an IP Address Go 87.5% Easy
1109 Corporate Flight Bookings
52.8% Medium
1110 Delete Nodes And Return Forest Go 67.0% Medium
1111 Maximum Nesting Depth of Two Valid Parentheses Strings Go 70.4% Medium
1112 Highest Grade For Each Student
69.4% Medium
1113 Reported Posts
64.1% Easy
1114 Print in Order
65.7% Easy
1115 Print FooBar Alternately
58.5% Medium
1116 Print Zero Even Odd
56.0% Medium
1117 Building H2O
52.6% Medium
1118 Number of Days in a Month
57.4% Easy
1119 Remove Vowels from a String
89.9% Easy
1120 Maximum Average Subtree
62.0% Medium
1121 Divide Array Into Increasing Sequences
56.8% Hard
1122 Relative Sort Array Go 67.7% Easy
1123 Lowest Common Ancestor of Deepest Leaves Go 66.8% Medium
1124 Longest Well-Performing Interval
32.7% Medium
1125 Smallest Sufficient Team
46.5% Hard
1126 Active Businesses
68.5% Medium
1127 User Purchase Platform
48.9% Hard
1128 Number of Equivalent Domino Pairs Go 47.3% Easy
1129 Shortest Path with Alternating Colors
38.9% Medium
1130 Minimum Cost Tree From Leaf Values
66.1% Medium
1131 Maximum of Absolute Value Expression
53.1% Medium
1132 Reported Posts II
34.4% Medium
1133 Largest Unique Number
66.9% Easy
1134 Armstrong Number
78.3% Easy
1135 Connecting Cities With Minimum Cost
57.5% Medium
1136 Parallel Courses
61.1% Hard
1137 N-th Tribonacci Number Go 55.9% Easy
1138 Alphabet Board Path
48.4% Medium
1139 Largest 1-Bordered Square
47.5% Medium
1140 Stone Game II
63.3% Medium
1141 User Activity for the Past 30 Days I
54.1% Easy
1142 User Activity for the Past 30 Days II
34.5% Easy
1143 Longest Common Subsequence
58.4% Medium
1144 Decrease Elements To Make Array Zigzag
45.4% Medium
1145 Binary Tree Coloring Game Go 51.3% Medium
1146 Snapshot Array
37.1% Medium
1147 Longest Chunked Palindrome Decomposition
58.6% Hard
1148 Article Views I
75.8% Easy
1149 Article Views II
48.1% Medium
1150 Check If a Number Is Majority Element in a Sorted Array
59.2% Easy
1151 Minimum Swaps to Group All 1's Together
59.3% Medium
1152 Analyze User Website Visit Pattern
43.5% Medium
1153 String Transforms Into Another String
35.8% Hard
1154 Day of the Year Go 49.3% Easy
1155 Number of Dice Rolls With Target Sum
49.1% Medium
1156 Swap For Longest Repeated Character Substring
48.9% Medium
1157 Online Majority Element In Subarray Go 38.9% Hard
1158 Market Analysis I
61.7% Medium
1159 Market Analysis II
52.9% Hard
1160 Find Words That Can Be Formed by Characters Go 67.4% Easy
1161 Maximum Level Sum of a Binary Tree
72.2% Medium
1162 As Far from Land as Possible
43.4% Medium
1163 Last Substring in Lexicographical Order
33.8% Hard
1164 Product Price at a Given Date
65.8% Medium
1165 Single-Row Keyboard
84.8% Easy
1166 Design File System
56.8% Medium
1167 Minimum Cost to Connect Sticks
62.7% Medium
1168 Optimize Water Distribution in a Village
60.9% Hard
1169 Invalid Transactions
31.2% Medium
1170 Compare Strings by Frequency of the Smallest Character Go 58.6% Easy
1171 Remove Zero Sum Consecutive Nodes from Linked List Go 41.4% Medium
1172 Dinner Plate Stacks
38.2% Hard
1173 Immediate Food Delivery I
80.4% Easy
1174 Immediate Food Delivery II
58.4% Medium
1175 Prime Arrangements Go 51.0% Easy
1176 Diet Plan Performance
53.9% Easy
1177 Can Make Palindrome from Substring
34.6% Medium
1178 Number of Valid Words for Each Puzzle
37.9% Hard
1179 Reformat Department Table
80.5% Easy
1180 Count Substrings with Only One Distinct Letter
77.0% Easy
1181 Before and After Puzzle
44.4% Medium
1182 Shortest Distance to Target Color
52.8% Medium
1183 Maximum Number of Ones
54.4% Hard
1184 Distance Between Bus Stops Go 54.4% Easy
1185 Day of the Week Go 64.0% Easy
1186 Maximum Subarray Sum with One Deletion
37.4% Medium
1187 Make Array Strictly Increasing
41.8% Hard
1188 Design Bounded Blocking Queue
70.5% Medium
1189 Maximum Number of Balloons Go 61.2% Easy
1190 Reverse Substrings Between Each Pair of Parentheses
61.5% Medium
1191 K-Concatenation Maximum Sum
25.9% Medium
1192 Critical Connections in a Network
48.6% Hard
1193 Monthly Transactions I
68.2% Medium
1194 Tournament Winners
52.8% Hard
1195 Fizz Buzz Multithreaded
68.3% Medium
1196 How Many Apples Can You Put into the Basket
68.1% Easy
1197 Minimum Knight Moves
36.1% Medium
1198 Find Smallest Common Element in All Rows
74.9% Medium
1199 Minimum Time to Build Blocks
37.3% Hard
1200 Minimum Absolute Difference Go 66.6% Easy
1201 Ugly Number III Go 25.9% Medium
1202 Smallest String With Swaps Go 46.5% Medium
1203 Sort Items by Groups Respecting Dependencies
47.6% Hard
1204 Last Person to Fit in the Elevator
69.7% Medium
1205 Monthly Transactions II
45.1% Medium
1206 Design Skiplist
57.4% Hard
1207 Unique Number of Occurrences Go 71.6% Easy
1208 Get Equal Substrings Within Budget Go 41.9% Medium
1209 Remove All Adjacent Duplicates in String II
56.8% Medium
1210 Minimum Moves to Reach Target with Rotations
45.2% Hard
1211 Queries Quality and Percentage
68.3% Easy
1212 Team Scores in Football Tournament
55.7% Medium
1213 Intersection of Three Sorted Arrays
78.9% Easy
1214 Two Sum BSTs
67.6% Medium
1215 Stepping Numbers
41.6% Medium
1216 Valid Palindrome III
47.7% Hard
1217 Play with Chips Go 64.3% Easy
1218 Longest Arithmetic Subsequence of Given Difference
44.5% Medium
1219 Path with Maximum Gold
65.1% Medium
1220 Count Vowels Permutation
53.9% Hard
1221 Split a String in Balanced Strings Go 83.2% Easy
1222 Queens That Can Attack the King
68.7% Medium
1223 Dice Roll Simulation
45.6% Medium
1224 Maximum Equal Frequency
33.5% Hard
1225 Report Contiguous Dates
61.2% Hard
1226 The Dining Philosophers
55.7% Medium
1227 Airplane Seat Assignment Probability
61.0% Medium
1228 Missing Number In Arithmetic Progression
52.6% Easy
1229 Meeting Scheduler
52.6% Medium
1230 Toss Strange Coins
48.7% Medium
1231 Divide Chocolate
52.3% Hard
1232 Check If It Is a Straight Line Go 45.3% Easy
1233 Remove Sub-Folders from the Filesystem
59.5% Medium
1234 Replace the Substring for Balanced String Go 33.3% Medium
1235 Maximum Profit in Job Scheduling Go 44.1% Hard
1236 Web Crawler
64.3% Medium
1237 Find Positive Integer Solution for a Given Equation
69.6% Easy
1238 Circular Permutation in Binary Representation
64.9% Medium
1239 Maximum Length of a Concatenated String with Unique Characters
47.8% Medium
1240 Tiling a Rectangle with the Fewest Squares
50.1% Hard
1241 Number of Comments per Post
67.0% Easy
1242 Web Crawler Multithreaded
45.9% Medium
1243 Array Transformation
51.0% Easy
1244 Design A Leaderboard
60.7% Medium
1245 Tree Diameter
60.0% Medium
1246 Palindrome Removal
46.0% Hard
1247 Minimum Swaps to Make Strings Equal
60.0% Medium
1248 Count Number of Nice Subarrays
56.4% Medium
1249 Minimum Remove to Make Valid Parentheses
62.5% Medium
1250 Check If It Is a Good Array
55.7% Hard
1251 Average Selling Price
81.4% Easy
1252 Cells with Odd Values in a Matrix Go 78.1% Easy
1253 Reconstruct a 2-Row Binary Matrix
40.4% Medium
1254 Number of Closed Islands Go 60.3% Medium
1255 Maximum Score Words Formed by Letters
69.3% Hard
1256 Encode Number
66.0% Medium
1257 Smallest Common Region
58.8% Medium
1258 Synonymous Sentences
64.4% Medium
1259 Handshakes That Don't Cross
53.5% Hard
1260 Shift 2D Grid Go 61.3% Easy
1261 Find Elements in a Contaminated Binary Tree
74.3% Medium
1262 Greatest Sum Divisible by Three
47.6% Medium
1263 Minimum Moves to Move a Box to Their Target Location
41.4% Hard
1264 Page Recommendations
67.5% Medium
1265 Print Immutable Linked List in Reverse
94.6% Medium
1266 Minimum Time Visiting All Points Go 79.6% Easy
1267 Count Servers that Communicate
57.9% Medium
1268 Search Suggestions System
63.3% Medium
1269 Number of Ways to Stay in the Same Place After Some Steps
43.2% Hard
1270 All People Report to the Given Manager
87.0% Medium
1271 Hexspeak
54.2% Easy
1272 Remove Interval
58.6% Medium
1273 Delete Tree Nodes
63.5% Medium
1274 Number of Ships in a Rectangle
66.5% Hard
1275 Find Winner on a Tic Tac Toe Game Go 52.9% Easy
1276 Number of Burgers with No Waste of Ingredients
49.6% Medium
1277 Count Square Submatrices with All Ones
73.2% Medium
1278 Palindrome Partitioning III
59.9% Hard
1279 Traffic Light Controlled Intersection
74.3% Easy
1280 Students and Examinations
72.1% Easy
1281 Subtract the Product and Sum of Digits of an Integer Go 85.2% Easy
1282 Group the People Given the Group Size They Belong To
83.9% Medium
1283 Find the Smallest Divisor Given a Threshold Go 47.6% Medium
1284 Minimum Number of Flips to Convert Binary Matrix to Zero Matrix
69.5% Hard
1285 Find the Start and End Number of Continuous Ranges
83.7% Medium
1286 Iterator for Combination
68.1% Medium
1287 Element Appearing More Than 25% In Sorted Array Go 60.2% Easy
1288 Remove Covered Intervals
58.0% Medium
1289 Minimum Falling Path Sum II
61.0% Hard
1290 Convert Binary Number in a Linked List to Integer Go 80.2% Easy
1291 Sequential Digits
53.4% Medium
1292 Maximum Side Length of a Square with Sum Less than or Equal to Threshold
48.5% Medium
1293 Shortest Path in a Grid with Obstacles Elimination
42.7% Hard
1294 Weather Type in Each Country
63.1% Easy
1295 Find Numbers with Even Number of Digits Go 81.6% Easy
1296 Divide Array in Sets of K Consecutive Numbers
53.7% Medium
1297 Maximum Number of Occurrences of a Substring
47.3% Medium
1298 Maximum Candies You Can Get from Boxes
58.9% Hard
1299 Replace Elements with Greatest Element on Right Side Go 75.4% Easy
1300 Sum of Mutated Array Closest to Target Go 44.2% Medium
1301 Number of Paths with Max Score
37.2% Hard
1302 Deepest Leaves Sum Go 83.6% Medium
1303 Find the Team Size
87.8% Easy
1304 Find N Unique Integers Sum up to Zero Go 76.3% Easy
1305 All Elements in Two Binary Search Trees Go 76.1% Medium
1306 Jump Game III Go 60.5% Medium
1307 Verbal Arithmetic Puzzle
37.6% Hard
1308 Running Total for Different Genders
84.0% Medium
1309 Decrypt String from Alphabet to Integer Mapping
76.7% Easy
1310 XOR Queries of a Subarray
68.6% Medium
1311 Get Watched Videos by Your Friends
43.1% Medium
1312 Minimum Insertion Steps to Make a String Palindrome
58.1% Hard
1313 Decompress Run-Length Encoded List Go 85.1% Easy
1314 Matrix Block Sum
73.7% Medium
1315 Sum of Nodes with Even-Valued Grandparent
83.5% Medium
1316 Distinct Echo Substrings
46.4% Hard
1317 Convert Integer to the Sum of Two No-Zero Integers Go 56.7% Easy
1318 Minimum Flips to Make a OR b Equal to c
62.8% Medium
1319 Number of Operations to Make Network Connected
53.1% Medium
1320 Minimum Distance to Type a Word Using Two Fingers
62.3% Hard
1321 Restaurant Growth
67.7% Medium
1322 Ads Performance
57.8% Easy
1323 Maximum 69 Number
77.9% Easy
1324 Print Words Vertically
58.0% Medium
1325 Delete Leaves With a Given Value
72.9% Medium
1326 Minimum Number of Taps to Open to Water a Garden
43.5% Hard
1327 List the Products Ordered in a Period
76.3% Easy
1328 Break a Palindrome
43.3% Medium
1329 Sort the Matrix Diagonally
78.4% Medium
1330 Reverse Subarray To Maximize Array Value
35.1% Hard
1331 Rank Transform of an Array
58.1% Easy
1332 Remove Palindromic Subsequences
60.0% Easy
1333 Filter Restaurants by Vegan-Friendly, Price and Distance
54.6% Medium
1334 Find the City With the Smallest Number of Neighbors at a Threshold Distance
44.5% Medium
1335 Minimum Difficulty of a Job Schedule
57.5% Hard
1336 Number of Transactions per Visit
43.5% Hard
1337 The K Weakest Rows in a Matrix
68.7% Easy
1338 Reduce Array Size to The Half
66.6% Medium
1339 Maximum Product of Splitted Binary Tree
37.2% Medium
1340 Jump Game V
57.5% Hard
1341 Movie Rating
56.6% Medium
1342 Number of Steps to Reduce a Number to Zero
86.3% Easy
1343 Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold
64.2% Medium
1344 Angle Between Hands of a Clock
61.4% Medium
1345 Jump Game IV
38.1% Hard
1346 Check If N and Its Double Exist
38.0% Easy
1347 Minimum Number of Steps to Make Two Strings Anagram
74.6% Medium
1348 Tweet Counts Per Frequency
29.0% Medium
1349 Maximum Students Taking Exam
41.9% Hard
1350 Students With Invalid Departments
89.4% Easy
1351 Count Negative Numbers in a Sorted Matrix
76.6% Easy
1352 Product of the Last K Numbers
43.6% Medium
1353 Maximum Number of Events That Can Be Attended
30.5% Medium
1354 Construct Target Array With Multiple Sums
31.9% Hard
1355 Activity Participants
69.2% Medium
1356 Sort Integers by The Number of 1 Bits
68.6% Easy
1357 Apply Discount Every n Orders
66.0% Medium
1358 Number of Substrings Containing All Three Characters
58.0% Medium
1359 Count All Valid Pickup and Delivery Options
57.9% Hard
1360 Number of Days Between Two Dates
48.8% Easy
1361 Validate Binary Tree Nodes
48.6% Medium
1362 Closest Divisors
56.7% Medium
1363 Largest Multiple of Three
33.5% Hard
1364 Number of Trusted Contacts of a Customer
75.3% Medium
1365 How Many Numbers Are Smaller Than the Current Number
85.6% Easy
1366 Rank Teams by Votes
52.4% Medium
1367 Linked List in Binary Tree
39.7% Medium
1368 Minimum Cost to Make at Least One Valid Path in a Grid
54.4% Hard
1369 Get the Second Most Recent Activity
64.7% Hard
1370 Increasing Decreasing String
75.6% Easy
1371 Find the Longest Substring Containing Vowels in Even Counts
57.3% Medium
1372 Longest ZigZag Path in a Binary Tree
54.0% Medium
1373 Maximum Sum BST in Binary Tree
40.2% Hard
1374 Generate a String With Characters That Have Odd Counts
75.4% Easy
1375 Bulb Switcher III
62.5% Medium
1376 Time Needed to Inform All Employees
55.5% Medium
1377 Frog Position After T Seconds
33.6% Hard
1378 Replace Employee ID With The Unique Identifier
87.4% Easy
1379 Find a Corresponding Node of a Binary Tree in a Clone of That Tree
83.8% Medium
1380 Lucky Numbers in a Matrix Go 71.4% Easy
1381 Design a Stack With Increment Operation
74.7% Medium
1382 Balance a Binary Search Tree
74.8% Medium
1383 Maximum Performance of a Team
31.8% Hard
1384 Total Sales Amount by Year
62.8% Hard
1385 Find the Distance Value Between Two Arrays Go 67.1% Easy
1386 Cinema Seat Allocation
34.8% Medium
1387 Sort Integers by The Power Value
70.1% Medium
1388 Pizza With 3n Slices
44.7% Hard
1389 Create Target Array in the Given Order Go 84.1% Easy
1390 Four Divisors
38.1% Medium
1391 Check if There is a Valid Path in a Grid
44.5% Medium
1392 Longest Happy Prefix
40.0% Hard
1393 Capital Gain/Loss
89.2% Medium
1394 Find Lucky Integer in an Array
64.5% Easy
1395 Count Number of Teams
81.9% Medium
1396 Design Underground System
64.7% Medium
1397 Find All Good Strings
37.2% Hard
1398 Customers Who Bought Products A and B but Not C
80.6% Medium
1399 Count Largest Group
65.0% Easy
1400 Construct K Palindrome Strings
60.4% Medium
1401 Circle and Rectangle Overlapping
41.8% Medium
1402 Reducing Dishes
72.8% Hard
1403 Minimum Subsequence in Non-Increasing Order
70.8% Easy
1404 Number of Steps to Reduce a Number in Binary Representation to One
50.3% Medium
1405 Longest Happy String
49.0% Medium
1406 Stone Game III
56.0% Hard
1407 Top Travellers
82.1% Easy
1408 String Matching in an Array
61.4% Easy
1409 Queries on a Permutation With Key
81.6% Medium
1410 HTML Entity Parser
53.9% Medium
1411 Number of Ways to Paint N × 3 Grid
61.2% Hard
1412 Find the Quiet Students in All Exams
66.6% Hard
1413 Minimum Value to Get Positive Step by Step Sum
65.2% Easy
1414 Find the Minimum Number of Fibonacci Numbers Whose Sum Is K
62.4% Medium
1415 The k-th Lexicographical String of All Happy Strings of Length n
70.4% Medium
1416 Restore The Array
36.7% Hard
1417 Reformat The String
55.0% Easy
1418 Display Table of Food Orders in a Restaurant
65.6% Medium
1419 Minimum Number of Frogs Croaking
46.3% Medium
1420 Build Array Where You Can Find The Maximum Exactly K Comparisons
65.2% Hard
1421 NPV Queries
80.5% Medium
1422 Maximum Score After Splitting a String
54.7% Easy
1423 Maximum Points You Can Obtain from Cards
42.5% Medium
1424 Diagonal Traverse II
42.3% Medium
1425 Constrained Subsequence Sum
44.1% Hard
1426 Counting Elements
58.7% Easy
1427 Perform String Shifts
53.0% Easy
1428 Leftmost Column with at Least a One
46.8% Medium
1429 First Unique Number
47.0% Medium
1430 Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree
44.8% Medium
1431 Kids With the Greatest Number of Candies
88.9% Easy
1432 Max Difference You Can Get From Changing an Integer
42.8% Medium
1433 Check If a String Can Break Another String
65.7% Medium
1434 Number of Ways to Wear Different Hats to Each Other
38.0% Hard
1435 Create a Session Bar Chart
76.7% Easy
1436 Destination City
77.3% Easy
1437 Check If All 1's Are at Least Length K Places Away
63.3% Medium
1438 Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit
41.9% Medium
1439 Find the Kth Smallest Sum of a Matrix With Sorted Rows
59.4% Hard
1440 Evaluate Boolean Expression
70.1% Medium
1441 Build an Array With Stack Operations
68.8% Easy
1442 Count Triplets That Can Form Two Arrays of Equal XOR
69.4% Medium
1443 Minimum Time to Collect All Apples in a Tree
55.5% Medium
1444 Number of Ways of Cutting a Pizza
52.7% Hard
1445 Apples & Oranges
87.2% Medium
1446 Consecutive Characters
60.4% Easy
1447 Simplified Fractions
61.0% Medium
1448 Count Good Nodes in Binary Tree
70.6% Medium
1449 Form Largest Integer With Digits That Add up to Target
41.8% Hard
1450 Number of Students Doing Homework at a Given Time
78.1% Easy
1451 Rearrange Words in a Sentence
54.8% Medium
1452 People Whose List of Favorite Companies Is Not a Subset of Another List
53.3% Medium
1453 Maximum Number of Darts Inside of a Circular Dartboard
33.7% Hard
1454 Active Users
37.5% Medium
1455 Check If a Word Occurs As a Prefix of Any Word in a Sentence Go 64.7% Easy
1456 Maximum Number of Vowels in a Substring of Given Length
52.4% Medium
1457 Pseudo-Palindromic Paths in a Binary Tree
67.2% Medium
1458 Max Dot Product of Two Subsequences
41.7% Hard
1459 Rectangles Area
61.5% Medium
1460 Make Two Arrays Equal by Reversing Sub-arrays
74.0% Easy
1461 Check If a String Contains All Binary Codes of Size K
44.6% Medium
1462 Course Schedule IV
41.7% Medium
1463 Cherry Pickup II
65.5% Hard
1464 Maximum Product of Two Elements in an Array Go 78.1% Easy
1465 Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts
30.8% Medium
1466 Reorder Routes to Make All Paths Lead to the City Zero
63.6% Medium
1467 Probability of a Two Boxes Having The Same Number of Distinct Balls
61.1% Hard
1468 Calculate Salaries
78.0% Medium
1469 Find All The Lonely Nodes
81.5% Easy
1470 Shuffle the Array Go 89.0% Easy
1471 The k Strongest Values in an Array
57.0% Medium
1472 Design Browser History
64.5% Medium
1473 Paint House III
48.1% Hard
1474 Delete N Nodes After M Nodes of a Linked List
74.2% Easy
1475 Final Prices With a Special Discount in a Shop
75.7% Easy
1476 Subrectangle Queries
90.5% Medium
1477 Find Two Non-overlapping Sub-arrays Each With Target Sum
29.8% Medium
1478 Allocate Mailboxes
55.0% Hard
1479 Sales by Day of the Week
83.4% Hard
1480 Running Sum of 1d Array
90.6% Easy
1481 Least Number of Unique Integers after K Removals
53.7% Medium
1482 Minimum Number of Days to Make m Bouquets
45.7% Medium
1483 Kth Ancestor of a Tree Node
27.6% Hard
1484 Group Sold Products By The Date
86.0% Easy
1485 Clone Binary Tree With Random Pointer
81.4% Medium
1486 XOR Operation in an Array
85.1% Easy
1487 Making File Names Unique
29.2% Medium
1488 Avoid Flood in The City
25.3% Medium
1489 Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree
50.5% Hard
1490 Clone N-ary Tree
84.7% Medium
1491 Average Salary Excluding the Minimum and Maximum Salary
70.2% Easy
1492 The kth Factor of n
68.0% Medium
1493 Longest Subarray of 1's After Deleting One Element
58.4% Medium
1494 Parallel Courses II
32.2% Hard
1495 Friendly Movies Streamed Last Month
52.9% Easy
1496 Path Crossing
55.9% Easy
1497 Check If Array Pairs Are Divisible by k
41.2% Medium
1498 Number of Subsequences That Satisfy the Given Sum Condition
36.7% Medium
1499 Max Value of Equation
44.6% Hard
1500 Design a File Sharing System
46.4% Medium
1501 Countries You Can Safely Invest In
63.8% Medium
1502 Can Make Arithmetic Progression From Sequence
73.4% Easy
1503 Last Moment Before All Ants Fall Out of a Plank
51.5% Medium
1504 Count Submatrices With All Ones
61.6% Medium
1505 Minimum Possible Integer After at Most K Adjacent Swaps On Digits
36.1% Hard
1506 Find Root of N-Ary Tree
79.8% Medium
1507 Reformat Date
60.5% Easy
1508 Range Sum of Sorted Subarray Sums
68.6% Medium
1509 Minimum Difference Between Largest and Smallest Value in Three Moves
50.9% Medium
1510 Stone Game IV
50.2% Hard
1511 Customer Order Frequency
77.0% Easy
1512 Number of Good Pairs
88.7% Easy
1513 Number of Substrings With Only 1s
40.4% Medium
1514 Path with Maximum Probability
36.5% Medium
1515 Best Position for a Service Centre
35.8% Hard
1516 Move Sub-Tree of N-Ary Tree
60.2% Hard
1517 Find Users With Valid E-Mails
71.2% Easy
1518 Water Bottles
63.1% Easy
1519 Number of Nodes in the Sub-Tree With the Same Label
35.1% Medium
1520 Maximum Number of Non-Overlapping Substrings
32.7% Hard
1521 Find a Value of a Mysterious Function Closest to Target
43.3% Hard
1522 Diameter of N-Ary Tree
70.0% Medium
1523 Count Odd Numbers in an Interval Range
55.7% Easy
1524 Number of Sub-arrays With Odd Sum
36.3% Medium
1525 Number of Good Ways to Split a String
70.0% Medium
1526 Minimum Number of Increments on Subarrays to Form a Target Array
57.5% Hard
1527 Patients With a Condition
88.4% Easy
1528 Shuffle String
86.1% Easy
1529 Bulb Switcher IV
70.4% Medium
1530 Number of Good Leaf Nodes Pairs
53.4% Medium
1531 String Compression II
28.6% Hard
1532 The Most Recent Three Orders
75.1% Medium
1533 Find the Index of the Large Integer
57.7% Medium
1534 Count Good Triplets
79.4% Easy
1535 Find the Winner of an Array Game
45.5% Medium
1536 Minimum Swaps to Arrange a Binary Grid
41.5% Medium
1537 Get the Maximum Score
35.7% Hard
1538 Guess the Majority in a Hidden Array
56.9% Medium
------------ ------------------------------------------------------- ------- ---------------- --------------- -------------
下面这些是免费的算法题，但是暂时还不能使用 Go 解答的：
Array
Problems List in there
String
Problems List in there
Two Pointers
- 双指针滑动窗口的经典写法。右指针不断往右移，移动到不能往右移动为止(具体条件根据题目而定)。当右指针到最右边以后，开始挪动左指针，释放窗口左边界。第 3 题，第 76 题，第 209 题，第 424 题，第 438 题，第 567 题，第 713 题，第 763 题，第 845 题，第 881 题，第 904 题，第 978 题，第 992 题，第 1004 题，第 1040 题，第 1052 题。
left, right := 0, -1
for left < len(s) {
if right+1 < len(s) && freq[s[right+1]-'a'] == 0 {
freq[s[right+1]-'a']++
right++
} else {
freq[s[left]-'a']--
left++
}
result = max(result, right-left+1)
}- 快慢指针可以查找重复数字，时间复杂度 O(n)，第 287 题。
- 替换字母以后，相同字母能出现连续最长的长度。第 424 题。
- SUM 问题集。第 1 题，第 15 题，第 16 题，第 18 题，第 167 题，第 923 题，第 1074 题。
Problems List in there
Linked List
- 巧妙的构造虚拟头结点。可以使遍历处理逻辑更加统一。
- 灵活使用递归。构造递归条件，使用递归可以巧妙的解题。不过需要注意有些题目不能使用递归，因为递归深度太深会导致超时和栈溢出。
- 链表区间逆序。第 92 题。
- 链表寻找中间节点。第 876 题。链表寻找倒数第 n 个节点。第 19 题。只需要一次遍历就可以得到答案。
- 合并 K 个有序链表。第 21 题，第 23 题。
- 链表归类。第 86 题，第 328 题。
- 链表排序，时间复杂度要求 O(n * log n)，空间复杂度 O(1)。只有一种做法，归并排序，至顶向下归并。第 148 题。
- 判断链表是否存在环，如果有环，输出环的交叉点的下标；判断 2 个链表是否有交叉点，如果有交叉点，输出交叉点。第 141 题，第 142 题，第 160 题。
Problems List in there
Stack
- 括号匹配问题及类似问题。第 20 题，第 921 题，第 1021 题。
- 栈的基本 pop 和 push 操作。第 71 题，第 150 题，第 155 题，第 224 题，第 225 题，第 232 题，第 946 题，第 1047 题。
- 利用栈进行编码问题。第 394 题，第 682 题，第 856 题，第 880 题。
- 单调栈。利用栈维护一个单调递增或者递减的下标数组。第 84 题，第 456 题，第 496 题，第 503 题，第 739 题，第 901 题，第 907 题，第 1019 题。
Problems List in there
Problems List in there
Dynamic Programming
Problems List in there
Backtracking
- 排列问题 Permutations。第 46 题，第 47 题。第 60 题，第 526 题，第 996 题。
- 组合问题 Combination。第 39 题，第 40 题，第 77 题，第 216 题。
- 排列和组合杂交问题。第 1079 题。
- N 皇后终极解法(二进制解法)。第 51 题，第 52 题。
- 数独问题。第 37 题。
- 四个方向搜索。第 79 题，第 212 题，第 980 题。
- 子集合问题。第 78 题，第 90 题。
- Trie。第 208 题，第 211 题。
- BFS 优化。第 126 题，第 127 题。
- DFS 模板。(只是一个例子，不对应任何题)
func combinationSum2(candidates []int, target int) [][]int {
if len(candidates) == 0 {
return [][]int{}
}
c, res := []int{}, [][]int{}
sort.Ints(candidates)
findcombinationSum2(candidates, target, 0, c, &res)
return res
}
func findcombinationSum2(nums []int, target, index int, c []int, res *[][]int) {
if target == 0 {
b := make([]int, len(c))
copy(b, c)
*res = append(*res, b)
return
}
for i := index; i < len(nums); i++ {
if i > index && nums[i] == nums[i-1] { // 这里是去重的关键逻辑
continue
}
if target >= nums[i] {
c = append(c, nums[i])
findcombinationSum2(nums, target-nums[i], i+1, c, res)
c = c[:len(c)-1]
}
}
}- BFS 模板。(只是一个例子，不对应任何题)
func updateMatrix_BFS(matrix [][]int) [][]int {
res := make([][]int, len(matrix))
if len(matrix) == 0 || len(matrix[0]) == 0 {
return res
}
queue := make([][]int, 0)
for i, _ := range matrix {
res[i] = make([]int, len(matrix[0]))
for j, _ := range res[i] {
if matrix[i][j] == 0 {
res[i][j] = -1
queue = append(queue, []int{i, j})
}
}
}
level := 1
for len(queue) > 0 {
size := len(queue)
for size > 0 {
size -= 1
node := queue[0]
queue = queue[1:]
i, j := node[0], node[1]
for _, direction := range [][]int{{-1, 0}, {1, 0}, {0, 1}, {0, -1}} {
x := i + direction[0]
y := j + direction[1]
if x < 0 || x >= len(matrix) || y < 0 || y >= len(matrix[0]) || res[x][y] < 0 || res[x][y] > 0 {
continue
}
res[x][y] = level
queue = append(queue, []int{x, y})
}
}
level++
}
for i, row := range res {
for j, cell := range row {
if cell == -1 {
res[i][j] = 0
}
}
}
return res
}Problems List in there
Depth First Search
Problems List in there
Breadth First Search
Problems List in there
Binary Search
- 二分搜索的经典写法。需要注意的三点：
- 循环退出条件，注意是 low <= high，而不是 low < high。
- mid 的取值，mid := low + (high-low)>>1
- low 和 high 的更新。low = mid + 1，high = mid - 1。
func binarySearchMatrix(nums []int, target int) int {
low, high := 0, len(nums)-1
for low <= high {
mid := low + (high-low)>>1
if nums[mid] == target {
return mid
} else if nums[mid] > target {
high = mid - 1
} else {
low = mid + 1
}
}
return -1
}- 二分搜索的变种写法。有 4 个基本变种:
- 查找第一个与 target 相等的元素，时间复杂度 O(logn)
- 查找最后一个与 target 相等的元素，时间复杂度 O(logn)
- 查找第一个大于等于 target 的元素，时间复杂度 O(logn)
- 查找最后一个小于等于 target 的元素，时间复杂度 O(logn)
// 二分查找第一个与 target 相等的元素，时间复杂度 O(logn)
func searchFirstEqualElement(nums []int, target int) int {
low, high := 0, len(nums)-1
for low <= high {
mid := low + ((high - low) >> 1)
if nums[mid] > target {
high = mid - 1
} else if nums[mid] < target {
low = mid + 1
} else {
if (mid == 0) || (nums[mid-1] != target) { // 找到第一个与 target 相等的元素
return mid
}
high = mid - 1
}
}
return -1
}
// 二分查找最后一个与 target 相等的元素，时间复杂度 O(logn)
func searchLastEqualElement(nums []int, target int) int {
low, high := 0, len(nums)-1
for low <= high {
mid := low + ((high - low) >> 1)
if nums[mid] > target {
high = mid - 1
} else if nums[mid] < target {
low = mid + 1
} else {
if (mid == len(nums)-1) || (nums[mid+1] != target) { // 找到最后一个与 target 相等的元素
return mid
}
low = mid + 1
}
}
return -1
}
// 二分查找第一个大于等于 target 的元素，时间复杂度 O(logn)
func searchFirstGreaterElement(nums []int, target int) int {
low, high := 0, len(nums)-1
for low <= high {
mid := low + ((high - low) >> 1)
if nums[mid] >= target {
if (mid == 0) || (nums[mid-1] < target) { // 找到第一个大于等于 target 的元素
return mid
}
high = mid - 1
} else {
low = mid + 1
}
}
return -1
}
// 二分查找最后一个小于等于 target 的元素，时间复杂度 O(logn)
func searchLastLessElement(nums []int, target int) int {
low, high := 0, len(nums)-1
for low <= high {
mid := low + ((high - low) >> 1)
if nums[mid] <= target {
if (mid == len(nums)-1) || (nums[mid+1] > target) { // 找到最后一个小于等于 target 的元素
return mid
}
low = mid + 1
} else {
high = mid - 1
}
}
return -1
}- 在基本有序的数组中用二分搜索。经典解法可以解，变种写法也可以写，常见的题型，在山峰数组中找山峰，在旋转有序数组中找分界点。第 33 题，第 81 题，第 153 题，第 154 题，第 162 题，第 852 题
func peakIndexInMountainArray(A []int) int {
low, high := 0, len(A)-1
for low < high {
mid := low + (high-low)>>1
// 如果 mid 较大，则左侧存在峰值，high = m，如果 mid + 1 较大，则右侧存在峰值，low = mid + 1
if A[mid] > A[mid+1] {
high = mid
} else {
low = mid + 1
}
}
return low
}- max-min 最大值最小化问题。求在最小满足条件的情况下的最大值。第 410 题，第 875 题，第 1011 题，第 1283 题。
Problems List in there
Problems List in there
Hash Table
Problems List in there
- 深刻的理解多路快排。第 75 题。
- 链表的排序，插入排序(第 147 题)和归并排序(第 148 题)
- 桶排序和基数排序。第 164 题。
- "摆动排序"。第 324 题。
- 两两不相邻的排序。第 767 题，第 1054 题。
- "饼子排序"。第 969 题。
Problems List in there
Bit Manipulation
- 异或的特性。第 136 题，第 268 题，第 389 题，第 421 题，
x ^ 0 = x x ^ 11111……1111 = ~x x ^ (~x) = 11111……1111 x ^ x = 0 a ^ b = c => a ^ c = b => b ^ c = a (交换律) a ^ b ^ c = a ^ (b ^ c) = (a ^ b）^ c (结合律)
- 构造特殊 Mask，将特殊位置放 0 或 1。
将 x 最右边的 n 位清零， x & ( ~0 << n ) 获取 x 的第 n 位值(0 或者 1)，(x >> n) & 1 获取 x 的第 n 位的幂值，x & (1 << (n - 1)) 仅将第 n 位置为 1，x | (1 << n) 仅将第 n 位置为 0，x & (~(1 << n)) 将 x 最高位至第 n 位(含)清零，x & ((1 << n) - 1) 将第 n 位至第 0 位(含)清零，x & (~((1 << (n + 1)) - 1)）
- 有特殊意义的 & 位操作运算。第 260 题，第 201 题，第 318 题，第 371 题，第 397 题，第 461 题，第 693 题，
X & 1 == 1 判断是否是奇数(偶数) X & = (X - 1) 将最低位(LSB)的 1 清零 X & -X 得到最低位(LSB)的 1 X & ~X = 0
Problems List in there
Union Find
- 灵活使用并查集的思想，熟练掌握并查集的模板，模板中有两种并查集的实现方式，一种是路径压缩 + 秩优化的版本，另外一种是计算每个集合中元素的个数 + 最大集合元素个数的版本，这两种版本都有各自使用的地方。能使用第一类并查集模板的题目有：第 128 题，第 130 题，第 547 题，第 684 题，第 721 题，第 765 题，第 778 题，第 839 题，第 924 题，第 928 题，第 947 题，第 952 题，第 959 题，第 990 题。能使用第二类并查集模板的题目有：第 803 题，第 952 题。第 803 题秩优化和统计集合个数这些地方会卡时间，如果不优化，会 TLE。
- 并查集是一种思想，有些题需要灵活使用这种思想，而不是死套模板，如第 399 题，这一题是 stringUnionFind，利用并查集思想实现的。这里每个节点是基于字符串和 map 的，而不是单纯的用 int 节点编号实现的。
- 有些题死套模板反而做不出来，比如第 685 题，这一题不能路径压缩和秩优化，因为题目中涉及到有向图，需要知道节点的前驱节点，如果路径压缩了，这一题就没法做了。这一题不需要路径压缩和秩优化。
- 灵活的抽象题目给的信息，将给定的信息合理的编号，使用并查集解题，并用 map 降低时间复杂度，如第 721 题，第 959 题。
- 关于地图，砖块，网格的题目，可以新建一个特殊节点，将四周边缘的砖块或者网格都 union() 到这个特殊节点上。第 130 题，第 803 题。
- 能用并查集的题目，一般也可以用 DFS 和 BFS 解答，只不过时间复杂度会高一点。
Problems List in there
Sliding Window
- 双指针滑动窗口的经典写法。右指针不断往右移，移动到不能往右移动为止(具体条件根据题目而定)。当右指针到最右边以后，开始挪动左指针，释放窗口左边界。第 3 题，第 76 题，第 209 题，第 424 题，第 438 题，第 567 题，第 713 题，第 763 题，第 845 题，第 881 题，第 904 题，第 978 题，第 992 题，第 1004 题，第 1040 题，第 1052 题。
left, right := 0, -1
for left < len(s) {
if right+1 < len(s) && freq[s[right+1]-'a'] == 0 {
freq[s[right+1]-'a']++
right++
} else {
freq[s[left]-'a']--
left++
}
result = max(result, right-left+1)
}- 滑动窗口经典题。第 239 题，第 480 题。
Problems List in there
Segment Tree
- 线段树的经典数组实现写法。将合并两个节点 pushUp 逻辑抽象出来了，可以实现任意操作(常见的操作有：加法，取 max，min 等等)。第 218 题，第 303 题，第 307 题，第 699 题。
- 计数线段树的经典写法。第 315 题，第 327 题，第 493 题。
- 线段树的树的实现写法。第 715 题，第 732 题。
- 区间懒惰更新。第 218 题，第 699 题。
- 离散化。离散化需要注意一个特殊情况：假如三个区间为 [1,10] [1,4] [6,10]，离散化后 x[1]=1,x[2]=4,x[3]=6,x[4]=10。第一个区间为 [1,4]，第二个区间为 [1,2]，第三个区间为 [3,4]，这样一来，区间一 = 区间二 + 区间三，这和离散前的模型不符，离散前，很明显，区间一 > 区间二 + 区间三。正确的做法是：在相差大于 1 的数间加一个数，例如在上面 1 4 6 10 中间加 5，即可 x[1]=1,x[2]=4,x[3]=5,x[4]=6,x[5]=10。这样处理之后，区间一是 1-5 ，区间二是 1-2 ，区间三是 4-5 。
- 灵活构建线段树。线段树节点可以存储多条信息，合并两个节点的 pushUp 操作也可以是多样的。第 850 题，第 1157 题。
线段树题型从简单到困难:
- 单点更新:
HDU 1166 敌兵布阵 update:单点增减 query:区间求和
HDU 1754 I Hate It update:单点替换 query:区间最值
HDU 1394 Minimum Inversion Number update:单点增减 query:区间求和
HDU 2795 Billboard query:区间求最大值的位子(直接把update的操作在query里做了) - 区间更新:
HDU 1698 Just a Hook update:成段替换 (由于只query一次总区间,所以可以直接输出 1 结点的信息)
POJ 3468 A Simple Problem with Integers update:成段增减 query:区间求和
POJ 2528 Mayor’s posters 离散化 + update:成段替换 query:简单hash
POJ 3225 Help with Intervals update:成段替换,区间异或 query:简单hash - 区间合并(这类题目会询问区间中满足条件的连续最长区间,所以PushUp的时候需要对左右儿子的区间进行合并):
POJ 3667 Hotel update:区间替换 query:询问满足条件的最左端点 - 扫描线(这类题目需要将一些操作排序,然后从左到右用一根扫描线扫过去最典型的就是矩形面积并,周长并等题):
HDU 1542 Atlantis update:区间增减 query:直接取根节点的值
HDU 1828 Picture update:区间增减 query:直接取根节点的值
Problems List in there
Binary Indexed Tree
Problems List in there
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