We have n buildings numbered from 0 to n - 1. Each building has a number of employees. It's transfer season, and some employees want to change the building they reside in. You are given an array requests where requests[i] = [fromi, toi] represents an employee's…

给你两个 非空 链表来代表两个非负整数。数字最高位位于链表开始位置。它们的每个节点只存储一位数字。将这两数相加会返回一个新的链表。 你可以假设除了数字 0 之外，这两个数字都不会以零开头。   示例1： 输入：l1 = [7,2,4,3], l2 = [5,6,4] 输出：[7,8,0,7] 示例2： 输入：l1 = [2,4,3], l2 = [5,6,4] 输出：[8,0,7] 示例3： 输入：l1 = [0], l2 = [0] 输出：[0]   提示：

Given two strings s and goal, return true if you can swap two letters in s so the result is equal to goal, otherwise, return false. Swapping letters is defined as taking two indices i and j (0-indexed) such that i != j and swapping the characters at s[i]…

给你一个下标从 0 开始的二维整数数组 nums 。一开始你的分数为 0 。你需要执行以下操作直到矩阵变为空：

Given an integer array nums where every element appears three times except for one, which appears exactly once. Find the single element and return it. You must implement a solution with a linear runtime complexity and use only constant extra space.   Example…

袋子中装有一些物品，每个物品上都标记着数字 1 、0 或 -1 。 给你四个非负整数 numOnes 、numZeros 、numNegOnes 和 k 。 袋子最初包含：

Given a binary array nums, you should delete one element from it. Return the size of the longest non-empty subarray containing only 1's in the resulting array. Return 0 if there is no such subarray.   Example 1: Input: nums = [1,1,0,1] Output: 3 Explanation:…

给你一个整数 finalSum 。请你将它拆分成若干个 互不相同 的正偶数之和，且拆分出来的正偶数数目 最多 。

Given an array of positive integers nums and a positive integer target, return the minimal length of a subarray whose sum is greater than or equal to target. If there is no such subarray, return 0 instead.   Example 1: Input: target = 7, nums = [2,3,1,2,4…

共有 k 位工人计划将 n 个箱子从旧仓库移动到新仓库。给你两个整数 n 和 k，以及一个二维整数数组 time ，数组的大小为 k x 4 ，其中 time[i] = [leftToRighti, pickOldi, rightToLefti, putNewi] 。 一条河将两座仓库分隔，只能通过一座桥通行。旧仓库位于河的右岸，新仓库在河的左岸。开始时，所有 k 位工人都在桥的左侧等待。为了移动这些箱子，第 i 位工人（下标从 0 开始）可以：

A teacher is writing a test with n true/false questions, with 'T' denoting true and 'F' denoting false. He wants to confuse the students by maximizing the number of consecutive questions with the same answer (multiple trues or multiple falses in a row). You…

给你一个下标从 1 开始的整数数组 numbers ，该数组已按 非递减顺序排列  ，请你从数组中找出满足相加之和等于目标数 target 的两个数。如果设这两个数分别是 numbers[index1] 和 numbers[index2] ，则 1 <= index1 < index2 <= numbers.length 。 以长度为 2 的整数数组 [index1, index2] 的形式返回这两个整数的下标 index1 和 index2。 你可以假设每个输入 只对应唯一的答案 ，而且你 不可以 重复使用相同的元素。…

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:

给你一个整数数组 nums ，判断是否存在三元组 [nums[i], nums[j], nums[k]] 满足 i != j、i != k 且 j != k ，同时还满足 nums[i] + nums[j] + nums[k] == 0 。请 你返回所有和为 0 且不重复的三元组。 注意：答案中不可以包含重复的三元组。     示例 1： 输入：nums = [-1,0,1,2,-1,-4] 输出：[[-1,-1,2],[-1,0,1]] 解释： nums[0] + nums[1] + nums[2] =…

The variance of a string is defined as the largest difference between the number of occurrences of any 2 characters present in the string. Note the two characters may or may not be the same. Given a string s consisting of lowercase English letters only, return…

给你一个长度为 n 的整数数组 nums 和 一个目标值 target。请你从 nums 中选出三个整数，使它们的和与 target 最接近。 返回这三个数的和。 假定每组输入只存在恰好一个解。   示例 1： 输入：nums = [-1,2,1,-4], target = 1 输出：2 解释：与 target 最接近的和是 2 (-1 + 2 + 1 = 2) 。 示例 2： 输入：nums = [0,0,0], target = 1 输出：0   提示：

Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. Note: A leaf is a node with no children.   Example 1: Input: root = [3,9,20,null,null,15,7] Output:…

一个下标从 0 开始的数组的 交替和 定义为 偶数 下标处元素之 和 减去 奇数 下标处元素之 和 。

Given the root of a binary tree, the value of a target node target, and an integer k, return an array of the values of all nodes that have a distance k from the target node. You can return the answer in any order.   Example 1: Input: root = [3,5,1,6,2,0,8…

给你一个正整数 n 。n 中的每一位数字都会按下述规则分配一个符号：