求条P2014（玄关）

#include <bits/stdc++.h>
using namespace std;
//using int = long long;
int n,m,s[305],f[305][305];
vector <int> k[305];
void dp(int x)
{
	f[x][1] = s[x];
	for (int i = 0;i < k[x].size();i++)
	{
		int y = k[x][i];
		dp(y);
		for (int j = m;j > 0;j--)
		{
			if (f[x][j] == -1)
			{
				continue;
			}
			for (int l = 1;l <= m - j;l++)
			{
				if (f[y][l] == -1)
				{
					continue;
				}
				f[x][j + l] = max(f[x][j + l],f[x][j] + f[y][l]);
			}
		}
	}
}
int main()
{
	cin >> n >> m;
	memset(f,-1,n + 1);
	f[0][0] = 0;
	for (int i = 1;i <= n;i++)
	{
		int x;
		cin >> x >> s[i];
		k[x].push_back(i);
	}
	dp(0);
	cout << f[0][m]; 
	return 0;
}