题目描述

模板题：二维前缀和

C++代码

#include <bits/stdc++.h>
using namespace std;

const int N = 1001;
int n, m, q;
int a[N][N], b[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++)
            b[i][j] = b[i][j - 1] + b[i - 1][j] - b[i - 1][j - 1] + a[i][j]; //构造前缀和
    while(q--){
        int x1, y1, x2, y2;
        scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
        printf("%d\n", b[x2][y2] - b[x1 - 1][y2] - b[x2][y1 - 1] + b[x1 - 1][y1 - 1]); //核心公式
    }
    return 0;
}