{ "data": { "question": { "questionId": "2343", "questionFrontendId": "2257", "categoryTitle": "Algorithms", "boundTopicId": 1456500, "title": "Count Unguarded Cells in the Grid", "titleSlug": "count-unguarded-cells-in-the-grid", "content": "

You are given two integers m and n representing a 0-indexed m x n grid. You are also given two 2D integer arrays guards and walls where guards[i] = [rowi, coli] and walls[j] = [rowj, colj] represent the positions of the ith guard and jth wall respectively.

\n\n

A guard can see every cell in the four cardinal directions (north, east, south, or west) starting from their position unless obstructed by a wall or another guard. A cell is guarded if there is at least one guard that can see it.

\n\n

Return the number of unoccupied cells that are not guarded.

\n\n

 

\n

Example 1:

\n\"\"\n
\nInput: m = 4, n = 6, guards = [[0,0],[1,1],[2,3]], walls = [[0,1],[2,2],[1,4]]\nOutput: 7\nExplanation: The guarded and unguarded cells are shown in red and green respectively in the above diagram.\nThere are a total of 7 unguarded cells, so we return 7.\n
\n\n

Example 2:

\n\"\"\n
\nInput: m = 3, n = 3, guards = [[1,1]], walls = [[0,1],[1,0],[2,1],[1,2]]\nOutput: 4\nExplanation: The unguarded cells are shown in green in the above diagram.\nThere are a total of 4 unguarded cells, so we return 4.\n
\n\n

 

\n

Constraints:

\n\n\n", "translatedTitle": "统计网格图中没有被保卫的格子数", "translatedContent": "

给你两个整数 m 和 n 表示一个下标从 0 开始的 m x n 网格图。同时给你两个二维整数数组 guards 和 walls ，其中 guards[i] = [rowi, coli] 且 walls[j] = [rowj, colj] ，分别表示第 i 个警卫和第 j 座墙所在的位置。

\n\n

一个警卫能看到 4 个坐标轴方向（即东、南、西、北）的 所有 格子，除非他们被一座墙或者另外一个警卫 挡住 了视线。如果一个格子能被 至少 一个警卫看到，那么我们说这个格子被 保卫 了。

\n\n

请你返回空格子中，有多少个格子是 没被保卫 的。

\n\n

 

\n\n

示例 1：

\n\n

\"\"

\n\n
输入：m = 4, n = 6, guards = [[0,0],[1,1],[2,3]], walls = [[0,1],[2,2],[1,4]]\n输出：7\n解释：上图中，被保卫和没有被保卫的格子分别用红色和绿色表示。\n总共有 7 个没有被保卫的格子，所以我们返回 7 。\n
\n\n

示例 2：

\n\n

\"\"

\n\n
输入：m = 3, n = 3, guards = [[1,1]], walls = [[0,1],[1,0],[2,1],[1,2]]\n输出：4\n解释：上图中，没有被保卫的格子用绿色表示。\n总共有 4 个没有被保卫的格子，所以我们返回 4 。\n
\n\n

 

\n\n

提示：

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