You are given a 2D integer matrix grid of size n x m, where each element is either 0, 1, or 2. A V-shaped diagonal segment is defined as:

给你一个大小为 n x n 的整数方阵 grid。返回一个经过如下调整的矩阵：

You are given an n x n square matrix of integers grid. Return the matrix such that:

请你判断一个 9 x 9 的数独是否有效。只需要 根据以下规则 ，验证已经填入的数字是否有效即可。

Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:

编写一个程序，通过填充空格来解决数独问题。 数独的解法需 遵循如下规则：

Write a program to solve a Sudoku puzzle by filling the empty cells. A sudoku solution must satisfy all of the following rules:

电子表格是一个网格，它有 26 列（从 'A' 到 'Z'）和指定数量的 rows。每个单元格可以存储一个 0 到 105 之间的整数值。 请你实现一个 Spreadsheet 类：

A spreadsheet is a grid with 26 columns (labeled from 'A' to 'Z') and a given number of rows. Each cell in the spreadsheet can hold an integer value between 0 and 105. Implement the Spreadsheet class:

给你一个 m x n 的矩阵，其中的值均为非负整数，代表二维高度图每个单元的高度，请计算图中形状最多能接多少体积的雨水。   示例 1: 输入: heightMap = [[1,4,3,1,3,2],[3,2,1,3,2,4],[2,3,3,2,3,1]] 输出: 4 解释: 下雨后，雨水将会被上图蓝色的方块中。总的接雨水量为1+2+1=4。 示例 2: 输入: heightMap = [[3,3,3,3,3],[3,2,2,2,3],[3,2,1,2,3],[3,2,2,2,3],[3,3,3,3,3]]…

Given an m x n integer matrix heightMap representing the height of each unit cell in a 2D elevation map, return the volume of water it can trap after raining.   Example 1: Input: heightMap = [[1,4,3,1,3,2],[3,2,1,3,2,4],[2,3,3,2,3,1]] Output: 4 Explanation:…