You are given an integer n. There is an undirected graph with n vertices, numbered from 0 to n - 1. You are given a 2D integer array edges where edges[i] = [ai, bi] denotes that there exists an undirected edge connecting vertices ai and bi. Return the number…

一个括号字符串是只由 '(' 和 ')' 组成的 非空 字符串。如果一个字符串满足下面 任意 一个条件，那么它就是有效的：

给你一个字符串数组 words 和一个字符串 s ，其中 words[i] 和 s 只包含 小写英文字母 。 请你返回 words 中是字符串 s 前缀 的 字符串数目 。 一个字符串的 前缀 是出现在字符串开头的子字符串。子字符串 是一个字符串中的连续一段字符序列。   示例 1： 输入：words = ["a","b","c","ab","bc","abc"], s = "abc" 输出：3 解释： words 中是 s = "abc" 前缀的字符串为： "a" ，"ab" 和 "abc" 。 所以…

You are given a positive integer days representing the total number of days an employee is available for work (starting from day 1). You are also given a 2D array meetings of size n where, meetings[i] = [start_i, end_i] represents the starting and ending…

给你一个下标从 0 开始、大小为 m x n 的二维矩阵 grid ，请你求解大小同样为 m x n 的答案矩阵 answer 。 矩阵 answer 中每个单元格 (r, c) 的值可以按下述方式进行计算：

You are given an integer n representing the dimensions of an n x n grid, with the origin at the bottom-left corner of the grid. You are also given a 2D array of coordinates rectangles, where rectangles[i] is in the form [startx, starty, endx, endy], representing…

You are given a 2D integer grid of size m x n and an integer x. In one operation, you can add x to or subtract x from any element in the grid. A uni-value grid is a grid where all the elements of it are equal. Return the minimum number of operations to make…

给你一个下标从 0 开始、长度为 n 的二进制字符串 s ，你可以对其执行两种操作：

An element x of an integer array arr of length m is dominant if more than half the elements of arr have a value of x. You are given a 0-indexed integer array nums of length n with one dominant element. You can split nums at an index i into two arrays nums[0…

给你一个下标从 0 开始的字符串 s ，重复执行下述操作 任意 次：

You are given an m x n integer matrix grid and an array queries of size k. Find an array answer of size k such that for each integer queries[i] you start in the top left cell of the matrix and repeat the following process:

给你一个 n 个节点的 有向图 ，节点编号为 0 到 n - 1 ，其中每个节点 至多 有一条出边。 图用一个大小为 n 下标从 0 开始的数组 edges 表示，节点 i 到节点 edges[i] 之间有一条有向边。如果节点 i 没有出边，那么 edges[i] == -1 。 请你返回图中的 最长 环，如果没有任何环，请返回 -1 。 一个环指的是起点和终点是 同一个 节点的路径。   示例 1： 输入：edges = [3,3,4,2,3] 输出去：3 解释：图中的最长环是：2 -> 4 -> 3…

You are given an array nums of n positive integers and an integer k. Initially, you start with a score of 1. You have to maximize your score by applying the following operation at most k times:

给你一个下标从 0 开始的字符串 s ，以及一个下标从 0 开始的整数数组 spaces 。 数组 spaces 描述原字符串中需要添加空格的下标。每个空格都应该插入到给定索引处的字符值 之前 。

You are given a string s. We want to partition the string into as many parts as possible so that each letter appears in at most one part. For example, the string "ababcc" can be partitioned into ["abab", "cc"], but partitions such as ["aba", "bcc"] or ["ab"…

给你一个字符串 s 和一个字符 letter ，返回在 s 中等于 letter 字符所占的 百分比 ，向下取整到最接近的百分比。   示例 1： 输入：s = "foobar", letter = "o" 输出：33 解释： 等于字母 'o' 的字符在 s 中占到的百分比是 2 / 6 * 100% = 33% ，向下取整，所以返回 33 。 示例 2： 输入：s = "jjjj", letter = "k" 输出：0 解释： 等于字母 'k' 的字符在 s 中占到的百分比是 0% ，所以返回 0 。…

You have k bags. You are given a 0-indexed integer array weights where weights[i] is the weight of the ith marble. You are also given the integer k. Divide the marbles into the k bags according to the following rules:

给你一个下标从 0 开始的二维整数数组 questions ，其中 questions[i] = [pointsi, brainpoweri] 。 这个数组表示一场考试里的一系列题目，你需要 按顺序 （也就是从问题 0 开始依次解决），针对每个问题选择 解决 或者 跳过 操作。解决问题 i 将让你 获得  pointsi 的分数，但是你将 无法 解决接下来的 brainpoweri 个问题（即只能跳过接下来的 brainpoweri 个问题）。如果你跳过问题 i ，你可以对下一个问题决定使用哪种操作。

You are given a 0-indexed 2D integer array questions where questions[i] = [pointsi, brainpoweri]. The array describes the questions of an exam, where you have to process the questions in order (i.e., starting from question 0) and make a decision whether to…

给你一个下标从 0 开始的整数数组 nums 。 请你从所有满足 i < j < k 的下标三元组 (i, j, k) 中，找出并返回下标三元组的最大值。如果所有满足条件的三元组的值都是负数，则返回 0 。 下标三元组 (i, j, k) 的值等于 (nums[i] - nums[j]) * nums[k] 。   示例 1： 输入：nums = [12,6,1,2,7] 输出：77 解释：下标三元组 (0, 2, 4) 的值是 (nums[0] - nums[2]) * nums[4] = 77 。 可以证明不存在值大于…

You are given a 0-indexed integer array nums. Return the maximum value over all triplets of indices (i, j, k) such that i < j < k. If all such triplets have a negative value, return 0. The value of a triplet of indices (i, j, k) is equal to (nums[i] - nums[j])…