子矩阵的和
二维前缀和
子矩阵
#include<bits/stdc++.h>
using namespace std;
const int N = 1010 ;
int n,m,q;
int a[N][N],s[N][N];//a是原数组,s存放前缀和数组
int main()
{
scanf("%d%d%d", &n, &m, &q);
for (int i = 1; i <= n; i ++ )
for (int j = 1; j <= m; j ++ )
scanf("%d", &a[i][j]);
//初始化 前缀和数组
for (int i = 1; i <= n; i ++ )
for (int j = 1; j <= m; j ++ )
s[i][j] = s[i-1][j] + s[i][j-1] - s[i-1][j-1] + a[i][j];
//询问
while(q--)
{
int x1,y1,x2,y2,re;
scanf("%d%d%d%d", &x1, &y1,&x2,&y2);
//子矩阵的和
re = s[x2][y2] - s[x1-1][y2] - s[x2][y1-1] + s[x1-1][y1-1];
printf("%d\n",re);
}
return 0;
}
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