99. 激光炸弹

https://www.acwing.com/problem/content/101/

#include<algorithm>
#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
const int N = 5e3+10;
int s[N][N];
int n, r;
int ans;
int c,k;
int main()
{
	cin >> n >> r;
	r=min(5001,r);
	while(n--)
	{
		int x,y,w;
		cin >> x >> y >> w;
		x++,y++;
		c=max(c,x),k=max(k,y);
		s[x][y]+=w;
	}
	for(int i=1;i<=5001;i++)
		for(int j=1;j<=5001;j++)
			s[i][j]+=s[i-1][j]+s[i][j-1]-s[i-1][j-1];
	for (int x = r; x <= 5001; x++)
		for (int y = r; y <= 5001; y++)
		{
			ans = max(ans, s[x][y] - s[x-r][y] - s[x][y-r] + s[x - r][y - r]);
		}
	cout << ans << endl;
	return 0;
}