送命二维前缀和

注意题目要的是左上角的坐标

#include <cstdio>
#include <algorithm>
#include <cmath>
int n, m, c, ans=-999999999, x, y;
int a[1005][1005], s[1005][1005];
int main()
{
	std::cin >> n >> m >> c;
	for(int i = 1;i <= n; i ++)
	{
		for(int j = 1;j <= m;j ++)
		{
			scanf("%d", &a[i][j]);
			s[i][j] = a[i][j] + s[i-1][j] + s[i][j-1] - s[i-1][j-1];
		}
	}
	for(int i = c;i <= n; i ++)
	{
		for(int j = c;j <= m; j ++)
		{
			int land=s[i][j] - s[i - c][j] - s[i][j - c] + s[i - c][j - c];
			if(land > ans)
			{
				ans = land;
				x = i;
				y = j;
			}
		}
	}
	std::cout << x - c + 1 << " " << y - c + 1;
	return 0;
}