题解上次有了见：http://blog.csdn.net/calculate23/article/details/79145503

本次AC代码：

#include<bits/stdc++.h>
using namespace std;

vector<int> tree[6010];
int dp[6010][2],zz[6010];

void tree_dfs(int father)
{
	int son;
	while(!tree[father].empty())
	{
		son=tree[father].back();
		tree_dfs(son);
		dp[father][1]+=dp[son][0];
		dp[father][0]+=max(dp[son][1],dp[son][0]);
		tree[father].pop_back();
	}
	return ;
}

int main()
{
//	freopen("e:\\input.txt","r",stdin);
//	freopen("e:\\output.txt","w",stdout);
	int i,j,n,a,b,father;
	while(~scanf("%d",&n))
	{
		memset(dp,0,sizeof(dp));
		memset(zz,0,sizeof(zz));
		for(i=1;i<=n;i++)
		{
			cin>>dp[i][1];
			tree[i].clear();
		}
		father=0;
		while(~scanf("%d%d",&a,&b) && (a+b))
		{
			tree[b].push_back(a);
			zz[a]=b;
			father=a;
		}
		while(zz[father])
			father=zz[father];
		tree_dfs(father);
		printf("%d\n",max(dp[father][1],dp[father][0]));
	}
	return 0;
}