补上题代码 hdu1520

#include<iostream>
#include<cmath>
#include<algorithm>
#include<vector>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<string>

using namespace std;

#define maxn 6005
struct node{
   int to,net;
}que[maxn<<1];
int head[maxn];
int n;
int dp[maxn][2],father[maxn];//dp[i][0]0表示不去，dp[i][1]1表示去了
bool visited[maxn];
int tot=0;

void addedge(int u,int v){
    que[tot].to=v;
    que[tot].net=head[u];
    head[u]=tot++;

    que[tot].to=u;
    que[tot].net=head[v];
    head[v]=tot++;

}

void tree_dp(int node)
{
    int i;
    visited[node] = 1;
    for(i=head[node]; i!=-1; i=que[i].net)
    {
        int v=que[i].to;
        if(!visited[v]&&father[v] == node)//i为下属
        {
            tree_dp(v);//递归调用孩子结点，从叶子结点开始dp
            //关键
        )   dp[node][1] += dp[v][0];//上司来,下属不来
            dp[node][0] +=max(dp[v][1],dp[v][0]);//上司不来，下属来、不来
        }
    }
}

int main()
{
    int i;
    int f,c,root;
    while(scanf("%d",&n)!=EOF)
    {
        tot=0;
        memset(head,-1,sizeof(head));
        memset(dp,0,sizeof(dp));
        memset(father,0,sizeof(father));
        memset(visited,0,sizeof(visited));
        for(i=1; i<=n; i++)
        {
            scanf("%d",&dp[i][1]);
        }
        root = 0;//记录父结点
        bool beg = 1;
        while (scanf("%d %d",&c,&f),c||f)
        {
            addedge(c,f);
            father[c] = f;
            if( root == c || beg )
            {
                root = f;
            }
        }
        while(father[root])//查找父结点
            root=father[root];
        tree_dp(root);
        int imax=max(dp[root][0],dp[root][1]);
        printf("%d
",imax);
    }
    return 0;

}