matrix-block-sum

java

python

python3

mysql

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oraclesql

csharp

javascript

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swift

kotlin

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golang

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scala

rust

racket

erlang

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cangjie

Algorithms

Given a <code>m x n</code> matrix <code>mat</code> and an integer <code>k</code>, return a matrix <code>answer</code> where each <code>answer[i][j]</code> is the sum of all elements <code>mat[r][c]</code> for:

<ul>
	<li><code>i - k &lt;= r &lt;= i + k,</code></li>
	<li><code>j - k &lt;= c &lt;= j + k</code>, and</li>
	<li><code>(r, c)</code> is a valid position in the matrix.</li>
</ul>

&nbsp;
Example 1:

<pre>
Input: mat = [[1,2,3],[4,5,6],[7,8,9]], k = 1
Output: [[12,21,16],[27,45,33],[24,39,28]]
</pre>

Example 2:

<pre>
Input: mat = [[1,2,3],[4,5,6],[7,8,9]], k = 2
Output: [[45,45,45],[45,45,45],[45,45,45]]
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>m ==&nbsp;mat.length</code></li>
	<li><code>n ==&nbsp;mat[i].length</code></li>
	<li><code>1 &lt;= m, n, k &lt;= 100</code></li>
	<li><code>1 &lt;= mat[i][j] &lt;= 100</code></li>
</ul>

matrixBlockSum

Matrix Block Sum

Stamping the Grid

stamping-the-grid

用邮票贴满网格图

Maximum Sum of an Hourglass

maximum-sum-of-an-hourglass

沙漏的最大总和

Design Neighbor Sum Service

design-neighbor-sum-service

设计相邻元素求和服务

Array

Matrix

Prefix Sum

给你一个 <code>m x n</code> 的矩阵 <code>mat</code> 和一个整数 <code>k</code> ，请你返回一个矩阵 <code>answer</code> ，其中每个 <code>answer[i][j]</code> 是所有满足下述条件的元素 <code>mat[r][c]</code> 的和： 

<ul>
	<li><code>i - k <= r <= i + k, </code></li>
	<li><code>j - k <= c <= j + k</code> 且</li>
	<li><code>(r, c)</code> 在矩阵内。</li>
</ul>

 

示例 1：

<pre>
输入：mat = [[1,2,3],[4,5,6],[7,8,9]], k = 1
输出：[[12,21,16],[27,45,33],[24,39,28]]
</pre>

示例 2：

<pre>
输入：mat = [[1,2,3],[4,5,6],[7,8,9]], k = 2
输出：[[45,45,45],[45,45,45],[45,45,45]]
</pre>

 

提示：

<ul>
	<li><code>m == mat.length</code></li>
	<li><code>n == mat[i].length</code></li>
	<li><code>1 <= m, n, k <= 100</code></li>
	<li><code>1 <= mat[i][j] <= 100</code></li>
</ul>