题目描述

s[i,j]的概念

以左上角(x1,y1)，右下角为(x2,y2)这一子矩阵的和

C++ 代码

#include <iostream>

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("%d\n", s[x2][y2] - s[x1 - 1][y2] - s[x2][y1 - 1] + s[x1 - 1][y1 - 1]); // 算部分和
    }
    return 0;
}