17| 激光炸弹

代码实现

typedef long long LL;
const int N = 5010; 
int n, m;
LL a[N][N], st[N][N];
int main()
{
	cin >> n >> m;
	while(n--)
	{
		int x, y, v; cin >> x >> y >> v;
		a[++x][++y] += v;
	}
	n = 5001;
	// 前缀和数组
	for(int i = 1; i <= n; i++)
	{
		for(int j = 1; j <= n; j++)
		{
			st[i][j] = st[i-1][j] + st[i][j-1] - st[i-1][j-1] + a[i][j];
		}
	 } 
	 // 枚举炸弹的位置
	 LL ret = 0;
	 m = min(m, n);
	 for (int x2 = m; x2 <= n; x2++)
	 {
	 	for (int y2 = m; y2 <= n; y2++)
	 	{
	 		int x1 = x2 - m + 1, y1 = y2 - m + 1;
	 		LL tmp = st[x2][y2] - st[x1-1][y2] - st[x2][y1-1] + st[x1-1][y1-1]; 
	 		ret = max(ret, tmp);
		 }
	  } 
	  cout << ret << endl;
	return 0;
 }