# LeetCode topic classification and interview questions collation

## Subject category

### Hash related

- [Question 1 : sum of two numbers](/src/hash相关/q1_两数之和)
- [Question 387 : the first unique character in the string](/src/hash相关/q387_字符串中的第一个唯一字符)

### Linked list operation

- [Question 2 : Add two numbers](/src/链表操作/q2_两数相加)
- [Question 19 : delete the Nth node from the bottom of the linked list](/src/链表操作/q19_删除链表的倒数第N个节点)
- [Question 25 : k set of flipped linked lists](/src/链表操作/q25_k个一组翻转链表)
- [Question 61 : rotating linked list](/src/链表操作/q61_旋转链表)
- [Question 138 : copy linked list with random pointer](/src/链表操作/q138_复制带随机指针的链表)
- [Question 206 : reverse linked list](/src/链表操作/q206_反转链表)

### Double pointer traversal/sliding window

- [Question 3 : Longest substring without repeated characters](/src/双指针遍历/q3_无重复字符的最长子串)
- [Question 11 : Container with the most water](/src/双指针遍历/q11_盛最多水的容器)
- [Question 15 : sum of three numbers](/src/双指针遍历/q15_三数之和)
- [Question 16 : closest sum of three numbers](/src/双指针遍历/q16_最接近的三数之和)
- [Question 26 : delete duplicates in the sorted array](/src/双指针遍历/q26_删除排序数组中的重复项)
- [Question 42 : trapping-rain-water](/src/双指针遍历/q42_接雨水)
- [Question 121 : The best time to buy and sell stocks](/src/双指针遍历/q121_买卖股票的最佳时机)
- [Question 209 : The smallest length sub-array](/src/双指针遍历/q209_长度最小的子数组)

### Fast and slow pointer traversal

- [Question 141 : circular linked list](/src/快慢指针遍历/q141_环形链表)
- [Question 202 : happy number](/src/快慢指针遍历/q202_快乐数)
- [Question 876 : intermediate node of linked list](/src/快慢指针遍历/q876_链表的中间结点)

### Interval merge

- [Question 56 : Merge interval](/src/区间合并/q56_合并区间)

### String manipulation

- [Question 6 : Zigzag transformation](/src/字符串操作/q6_Z字形变换)
- [Question 14 : longest common prefix](/src/字符串操作/q14_最长公共前缀)
- [Question 763 : Dividing letter interval](/src/字符串操作/q763_划分字母区间)

### Digital operation

- [Question 7 : integer inversion](/src/数字操作/q7_整数反转)
- [Question 8 : string conversion integer](/src/数字操作/q8_字符串转换整数)
- [Question 9 : Palindrome Number](/src/数字操作/q9_回文数)
- [Question 43 : string multiplication](/src/数字操作/q43_字符串相乘)
- [Question 172 : zero after factorial](/src/数字操作/q172_阶乘后的零)
- [Question 258 : Add everybody](/src/数字操作/q258_各位相加)

### Array operations

- [Question 54 : spiral matrix](/src/数组操作/q54_螺旋矩阵)
- [Question 73 : Zero Matrix](/src/数组操作/q73_矩阵置零)
- [Question 78 : subset](/src/数组操作/q78_子集)
- [Question 384 : scrambling array](/src/数组操作/q384_打乱数组)
- [Question 581 : shortest unordered continuous subarray](/src/数组操作/q581_最短无序连续子数组)
- [Question 945 : Minimum increment to make the array unique](/src/数组操作/q945_使数组唯一的最小增量)

### Stack related

- [Question 20 : valid brackets](/src/栈相关/q20_有效的括号)
- [Question 32 : longest valid bracket](/src/栈相关/q32_最长有效括号)
- [Question 155 : Minimal stack](/src/栈相关/q155_最小栈)
- [Question 224 : basic calculator](/src/栈相关/q224_基本计算器)
- [Question 232 : implement queue with stack](/src/栈相关/q232_用栈实现队列)
- [Question 316 : remove duplicate letters](/src/栈相关/q316_去除重复字母)

### Heap related

- [Question 215 : the Kth largest element in the array](/src/堆相关/q215_数组中的第K个最大元素)
- [Question 347 : top K high frequency elements](/src/堆相关/q347_前K个高频元素)

### Recursion

- [Question 21 : merge two ordered linked lists](/src/递归/q21_合并两个有序链表)
- [Question 101 : symmetric binary tree](/src/递归/q101_对称二叉树)
- [Question 104 : Maximum Depth of Binary Tree](/src/递归/q104_二叉树的最大深度)
- [Question 226 : flip binary tree](/src/递归/q226_翻转二叉树)
- [Question 236 : The nearest common ancestor of the binary tree](/src/递归/q236_二叉树的最近公共祖先)

### Divide and Conquer/Dichotomy

- [Question 23 : Merge K sorted lists](/src/分治法/q23_合并K个排序链表)
- [Question 33 : Search rotating sorted array](/src/分治法/q33_搜索旋转排序数组)
- [Question 34 : Find the first and last position of an element in the sorted array](/src/分治法/q34_在排序数组中查找元素的第一个和最后一个位置)

### Dynamic Planning

- [Question 5 : longest palindrome substring](/src/动态规划/q5_最长回文子串)
- [Question 53 : Maximum Subsequence Sum](/src/动态规划/q53_最大子序和)
- [Question 62 : different path](/src/动态规划/q62_不同路径)
- [Question 64 : Minimum path sum](/src/动态规划/q64_最小路径和)
- [Question 70 : stair climbing](/src/动态规划/q70_爬楼梯)
- [Question 118 : Pascal's Triangle](/src/动态规划/q118_杨辉三角)
- [Question 300 : Longest Ascending Subsequence](/src/动态规划/q300_最长上升子序列)
- [Question 1143 : longest common subsequence](/src/动态规划/q1143_最长公共子序列)
- [Question 1277 : square submatrix with all 1s](/src/动态规划/q1277_统计全为1的正方形子矩阵)

### Backtracking

- [Question 10 : regular expression matching](/src/回溯法/q10_正则表达式匹配)
- [Question 22 : bracket generation](/src/回溯法/q22_括号生成)
- [Question 40 : combined sum 2](/src/回溯法/q40_组合总和2)
- [Question 46 : all permutation](/src/回溯法/q46_全排列)

### Tree traversal

- [Question 94 : In-order traversal of binary tree](/src/树的遍历/q94_二叉树的中序遍历)
- [Question 102 : Binary tree traversal](/src/树的遍历/q102_二叉树的层次遍历)
- [Question 110 : balanced binary tree](/src/树的遍历/q110_平衡二叉树)
- [Question 144 : Preorder traversal of binary tree](/src/树的遍历/q144_二叉树的前序遍历)
- [Question 145 : Post-order traversal of binary tree](/src/树的遍历/q145_二叉树的后序遍历)

### Binary search tree related

- [Question 98 : Verify Binary Search Tree](/src/二叉搜索树相关/q98_验证二叉搜索树)
- [Question 450 : delete nodes in binary search tree](/src/二叉搜索树相关/q450_删除二叉搜索树中的节点)
- [Question 701 : insert operation in binary search tree](/src/二叉搜索树相关/q701_二叉搜索树中的插入操作)

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## Interview questions finishing

-[Interview Questions Finishing](/Rocket.md)