Anniversary party POJ

#include<iostream>#include<cstdio>#include<cstring>using namespace std;int  vis[6003],father[6003],dp[6003][2],num;void dfs(int par){    vis[par]=1;    for(int i=1;i<=num;i++)    if(!vis[i]&&father[i]==par)    {        dfs(i);        dp[par][1]+=dp[i][0];        dp[par][0]+=max(dp[i][0],dp[i][1]);     }}int main(){    while(~scanf("%d",&num))    {        for(int i=1;i<=num;i++)        scanf("%d",&dp[i][1]);        memset(vis,0,sizeof(vis));        memset(father,0,sizeof(father));        int em,bo,root;        while(~scanf("%d %d",&em,&bo),em||bo)        {father[em]=bo;         root=bo;        }        dfs(root);        cout<<max(dp[root][1],dp[root][0])<<endl;    }    return 0;}