学步园

题目大意：见NOIP2014 Day2T1

CODE：

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define MAX 5110
using namespace std;

int cnt,range;
int sum[MAX][MAX];

inline int Calc(int x,int y)
{
	return sum[x + range][y + range] - sum[x - 1][y + range] - sum[x + range][y - 1] + sum[x - 1][y - 1];
}

int main()
{
	cin >> cnt >> range;
	--range;
	for(int x,y,z,i = 1; i <= cnt; ++i) {
		scanf("%d%d%d",&x,&y,&z);
		sum[x + 1][y + 1] += z;
	}
	for(int i = 1; i <= 5010; ++i)
		for(int j = 1; j <= 5010; ++j)
			sum[i][j] += sum[i - 1][j] + sum[i][j - 1] - sum[i - 1][j - 1];
	int ans = 0;
	for(int i = 1; i <= 5001 - range; ++i)
		for(int j = 1; j <= 5001 - range; ++j)
			ans = max(ans,Calc(i,j));
	cout << ans << endl;
	return 0;
}