原文链接: https://leetcode-cn.com/problems/reorder-list 英文原文You are given the head of a singly linked-list. The list can be represented as: L0 → L1 → … → Ln - 1 → Ln Reorder the list to be on the following form: L0 → Ln &r…

原文链接: https://leetcode-cn.com/problems/binary-tree-preorder-traversal 英文原文Given the root of a binary tree, return the preorder traversal of its nodes' values. Example 1: Input: root = [1,null,2,3] Output: [1,2,3] Example 2: Input: root = [] Output: […

原文链接: https://leetcode-cn.com/problems/binary-tree-postorder-traversal 英文原文Given the root of a binary tree, return the postorder traversal of its nodes' values. Example 1: Input: root = [1,null,2,3] Output: [3,2,1] Example 2: Input: root = [] Output:…

原文链接: https://leetcode-cn.com/problems/lru-cache 英文原文Design a data structure that follows the constraints of a Least Recently Used (LRU) cache. Implement the LRUCache class: LRUCache(int capacity) Initialize the LRU cache with positive size capacity.…

原文链接: https://leetcode-cn.com/problems/insertion-sort-list 英文原文Given the head of a singly linked list, sort the list using insertion sort, and return the sorted list's head. The steps of the insertion sort algorithm: Insertion sort iterates, consumin…

原文链接: https://leetcode-cn.com/problems/max-points-on-a-line 英文原文Given an array of points where points[i] = [xi, yi] represents a point on the X-Y plane, return the maximum number of points that lie on the same straight line. Example 1: Input: points …

原文链接: https://leetcode-cn.com/problems/evaluate-reverse-polish-notation 英文原文Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, and /. Each operand may be an integer or another expression. Note that…

原文链接: https://leetcode-cn.com/problems/reverse-words-in-a-string 英文原文Given an input string s, reverse the order of the words. A word is defined as a sequence of non-space characters. The words in s will be separated by at least one space. Return a st…

原文链接: https://leetcode-cn.com/problems/maximum-product-subarray 英文原文Given an integer array nums, find a contiguous non-empty subarray within the array that has the largest product, and return the product. It is guaranteed that the answer will fit in …

原文链接: https://leetcode-cn.com/problems/find-minimum-in-rotated-sorted-array 英文原文Suppose an array of length n sorted in ascending order is rotated between 1 and n times. For example, the array nums = [0,1,2,4,5,6,7] might become: [4,5,6,7,0,1,2] if it…

原文链接: https://leetcode-cn.com/problems/find-minimum-in-rotated-sorted-array-ii 英文原文Suppose an array of length n sorted in ascending order is rotated between 1 and n times. For example, the array nums = [0,1,4,4,5,6,7] might become: [4,5,6,7,0,1,4] if…

原文链接: https://leetcode-cn.com/problems/min-stack 英文原文Design a stack that supports push, pop, top, and retrieving the minimum element in constant time. Implement the MinStack class: MinStack() initializes the stack object. void push(int val) pushes th…

原文链接: https://leetcode-cn.com/problems/intersection-of-two-linked-lists 英文原文Given the heads of two singly linked-lists headA and headB, return the node at which the two lists intersect. If the two linked lists have no intersection at all, return null…

原文链接: https://leetcode-cn.com/problems/find-peak-element 英文原文A peak element is an element that is strictly greater than its neighbors. Given an integer array nums, find a peak element, and return its index. If the array contains multiple peaks, retur…

原文链接: https://leetcode-cn.com/problems/maximum-gap 英文原文Given an integer array nums, return the maximum difference between two successive elements in its sorted form. If the array contains less than two elements, return 0. You must write an algorithm …

原文链接: https://leetcode-cn.com/problems/compare-version-numbers 英文原文Given two version numbers, version1 and version2, compare them. Version numbers consist of one or more revisions joined by a dot '.'. Each revision consists of digits and may contain …

原文链接: https://leetcode-cn.com/problems/fraction-to-recurring-decimal 英文原文Given two integers representing the numerator and denominator of a fraction, return the fraction in string format. If the fractional part is repeating, enclose the repeating par…

原文链接: https://leetcode-cn.com/problems/two-sum-ii-input-array-is-sorted 英文原文Given a 1-indexed array of integers numbers that is already sorted in non-decreasing order, find two numbers such that they add up to a specific target number. Let these two …

原文链接: https://leetcode-cn.com/problems/excel-sheet-column-title 英文原文Given an integer columnNumber, return its corresponding column title as it appears in an Excel sheet. For example: A -> 1 B -> 2 C -> 3 ... Z -> 26 AA -> 27 AB -> 28 ... Example 1: I…

原文链接: https://leetcode-cn.com/problems/majority-element 英文原文Given an array nums of size n, return the majority element. The majority element is the element that appears more than ⌊n / 2⌋ times. You may assume that the majority element a…

原文链接: https://leetcode-cn.com/problems/excel-sheet-column-number 英文原文Given a string columnTitle that represents the column title as appear in an Excel sheet, return its corresponding column number. For example: A -> 1 B -> 2 C -> 3 ... Z -> 26 AA -> …

原文链接: https://leetcode-cn.com/problems/factorial-trailing-zeroes 英文原文Given an integer n, return the number of trailing zeroes in n!. Note that n! = n * (n - 1) * (n - 2) * ... * 3 * 2 * 1. Example 1: Input: n = 3 Output: 0 Explanation: 3! = 6, no tra…

原文链接: https://leetcode-cn.com/problems/binary-search-tree-iterator 英文原文Implement the BSTIterator class that represents an iterator over the in-order traversal of a binary search tree (BST): BSTIterator(TreeNode root) Initializes an object of the BSTI…

原文链接: https://leetcode-cn.com/problems/dungeon-game 英文原文The demons had captured the princess and imprisoned her in the bottom-right corner of a dungeon. The dungeon consists of m x n rooms laid out in a 2D grid. Our valiant knight was initially posit…

原文链接: https://leetcode-cn.com/problems/combine-two-tables 英文原文Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | personId | int | | lastName | varchar | | firstName | varchar | +-------------+---------+ personI…

原文链接: https://leetcode-cn.com/problems/second-highest-salary 英文原文Table: Employee +-------------+------+ | Column Name | Type | +-------------+------+ | id | int | | salary | int | +-------------+------+ id is the primary key column for this table. Ea…

原文链接: https://leetcode-cn.com/problems/nth-highest-salary 英文原文Table: Employee +-------------+------+ | Column Name | Type | +-------------+------+ | id | int | | salary | int | +-------------+------+ id is the primary key column for this table. Each …

原文链接: https://leetcode-cn.com/problems/rank-scores 英文原文Table: Scores +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | score | decimal | +-------------+---------+ id is the primary key for this table. Each row …

原文链接: https://leetcode-cn.com/problems/consecutive-numbers 英文原文Table: Logs +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | num | varchar | +-------------+---------+ id is the primary key for this table. Write…

原文链接: https://leetcode-cn.com/problems/largest-number 英文原文Given a list of non-negative integers nums, arrange them such that they form the largest number. Note: The result may be very large, so you need to return a string instead of an integer. Examp…