C++ 子矩阵和

#include 
#include 

using namespace std;

const int N = 1010;

int n, m, q;
int a[N][N], s[N][N];

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]);
    
    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];    // 求前缀和
    
    while ( q-- )
    {
        int x1, y1, x2, y2;
        scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
        printf("%dn", s[x2][y2] - s[x1 - 1][y2] - s[x2][y1 - 1] + s[x1 - 1][y1 - 1]);  // 求子矩阵和
    }
    
    return 0;
}