백준 11660번 : 구간 합 구하기 5 - 누적합 C++

https://www.acmicpc.net/problem/11660

11660번: 구간 합 구하기 5

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


int n, m;
int psum[1025][1025];

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);

	cin >> n >> m;

	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			int a;
			cin >> a;
			psum[i + 1][j + 1] = psum[i + 1][j] + psum[i][j + 1] - psum[i][j] + a;
		}
	}

	for (int i = 0; i < m; i++) {
		int x1, x2, y1, y2;
		cin >> x1 >> y1 >> x2 >> y2;
		cout << psum[x2][y2] - psum[x2][y1 - 1] - psum[x1 - 1][y2] + psum[x1-1][y1-1] << '\n';
	}



	return 0;
}