largest-local-values-in-a-matrix

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Algorithms

You are given an <code>n x n</code> integer matrix <code>grid</code>.

Generate an integer matrix <code>maxLocal</code> of size <code>(n - 2) x (n - 2)</code> such that:

<ul>
	<li><code>maxLocal[i][j]</code> is equal to the largest value of the <code>3 x 3</code> matrix in <code>grid</code> centered around row <code>i + 1</code> and column <code>j + 1</code>.</li>
</ul>

In other words, we want to find the largest value in every contiguous <code>3 x 3</code> matrix in <code>grid</code>.

Return the generated matrix.

&nbsp;
Example 1:
<img alt="" src="https://assets.leetcode.com/uploads/2022/06/21/ex1.png" style="width: 371px; height: 210px;" />
<pre>
Input: grid = [[9,9,8,1],[5,6,2,6],[8,2,6,4],[6,2,2,2]]
Output: [[9,9],[8,6]]
Explanation: The diagram above shows the original matrix and the generated matrix.
Notice that each value in the generated matrix corresponds to the largest value of a contiguous 3 x 3 matrix in grid.</pre>

Example 2:
<img alt="" src="https://assets.leetcode.com/uploads/2022/07/02/ex2new2.png" style="width: 436px; height: 240px;" />
<pre>
Input: grid = [[1,1,1,1,1],[1,1,1,1,1],[1,1,2,1,1],[1,1,1,1,1],[1,1,1,1,1]]
Output: [[2,2,2],[2,2,2],[2,2,2]]
Explanation: Notice that the 2 is contained within every contiguous 3 x 3 matrix in grid.
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>n == grid.length == grid[i].length</code></li>
	<li><code>3 &lt;= n &lt;= 100</code></li>
	<li><code>1 &lt;= grid[i][j] &lt;= 100</code></li>
</ul>

largestLocal

Largest Local Values in a Matrix

Array

Matrix

给你一个大小为 <code>n x n</code> 的整数矩阵 <code>grid</code> 。

生成一个大小为&nbsp;<code>(n - 2) x (n - 2)</code> 的整数矩阵&nbsp; <code>maxLocal</code> ，并满足：

<ul>
	<li><code>maxLocal[i][j]</code> 等于 <code>grid</code> 中以 <code>i + 1</code> 行和 <code>j + 1</code> 列为中心的 <code>3 x 3</code> 矩阵中的 最大值 。</li>
</ul>

换句话说，我们希望找出 <code>grid</code> 中每个&nbsp;<code>3 x 3</code> 矩阵中的最大值。

返回生成的矩阵。

&nbsp;

示例 1：

<img alt="" src="https://assets.leetcode.com/uploads/2022/06/21/ex1.png" style="width: 371px; height: 210px;" />

<pre>
输入：grid = [[9,9,8,1],[5,6,2,6],[8,2,6,4],[6,2,2,2]]
输出：[[9,9],[8,6]]
解释：原矩阵和生成的矩阵如上图所示。
注意，生成的矩阵中，每个值都对应 grid 中一个相接的 3 x 3 矩阵的最大值。</pre>

示例 2：

<img alt="" src="https://assets.leetcode.com/uploads/2022/07/02/ex2new2.png" style="width: 436px; height: 240px;" />

<pre>
输入：grid = [[1,1,1,1,1],[1,1,1,1,1],[1,1,2,1,1],[1,1,1,1,1],[1,1,1,1,1]]
输出：[[2,2,2],[2,2,2],[2,2,2]]
解释：注意，2 包含在 grid 中每个 3 x 3 的矩阵中。
</pre>

&nbsp;

提示：

<ul>
	<li><code>n == grid.length == grid[i].length</code></li>
	<li><code>3 &lt;= n &lt;= 100</code></li>
	<li><code>1 &lt;= grid[i][j] &lt;= 100</code></li>
</ul>