HDU 1520 Anniversary party

http://acm.bjtu.edu.cn/vjudge/problem/viewProblem.action?id=669

最最基础的树形dp，父子兄弟结构太爽了，学自hh博客

#include <iostream>
using namespace std ;
struct Tree{
    int father ;
    int child ;
    int brother ;
    int happy ;
    int temp ;
    int MAX(){
        return max(happy,temp) ;
    }
    void init(){
        father=child=brother=temp=0 ;
    }
}tree[6001] ;
void dfs(int idx)
{
    int child ;
    child=tree[idx].child ;
    while(child)
    {
        dfs(child) ;
        tree[idx].happy+=tree[child].temp ;
        tree[idx].temp+=tree[child].MAX() ;
        child=tree[child].brother ;
    }
}
int main()
{
    int n ;
    while(~scanf("%d",&n))
    {
        for(int i=1;i<=n;i++)
        {
            scanf("%d",&tree[i].happy) ;
            tree[i].init() ;
        }
        int l,k ;
        while(scanf("%d%d",&l,&k),l||k)
        {
            tree[l].father=k ;
            tree[l].brother=tree[k].child ;
            tree[k].child=l ; 
        }
        for(int i=1;i<=n;i++)
            if(!tree[i].father)
            {
                dfs(i) ;
                printf("%d\n",tree[i].MAX()) ;
                break ;
            }
    }
    return 0 ;
}