二维前缀和,主要是把示意图画明白,明白每个前缀和的作用的范围
#include <iostream>
using namespace std;
const int N = 1010;
int a[N][N], b[N][N];
int main()
{
int m, n, q, x1, x2, y1, y2;
scanf("%d%d%d", &n, &m, &q);
for(int i = 1; i <= n; i ++ )
for(int j = 1; j <= m; j ++ )
scanf("%d", &b[i][j]);
for(int i = 1; i <= n; i ++ )
for(int j = 1; j <= m; j ++ )
a[i][j] = a[i - 1][j] + a[i][j - 1] - a[i - 1][j - 1] + b[i][j];
while(q--)
{
scanf("%d%d%d%d",&x1, &y1, &x2, &y2);
printf("%d\n", a[x2][y2] - a[x1 - 1][y2] - a[x2][y1 - 1] + a[x1 - 1][y1 - 1]);
}
return 0;
}