二维前缀和

#include<bits/stdc++.h>
using namespace std;
const int N = 1005;
int a[N][N];
int n,m,q;
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]);
			a[i][j] = a[i-1][j]+a[i][j]+a[i][j-1]-a[i-1][j-1];
		}
	}
	while(q--){
		int x1,y1,x2,y2;
		scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
		int ans = a[x2][y2]-a[x1-1][y2]-a[x2][y1-1]+a[x1-1][y1-1];
		printf("%d\n",ans);
	}
}

796. 子矩阵的和 - AcWing题库