hdu 1520 Anniversary party

#include <iostream>
#include <cstring>
#include <cstdio>
#define Max 6001
using namespace std;
int n,l[Max],k[Max];
int rating[Max],fir[Max],nex[Max],vis[Max];
int dp[2][Max];
void dfs(int d)
{
    int kk = fir[d];
    while(kk != -1)
    {
        dfs(l[kk]);
        dp[0][d] += max(dp[0][l[kk]],dp[1][l[kk]]);///当前点不出席的话 他的下一级出不出都可以
        dp[1][d] += dp[0][l[kk]];///他出席 下一级就不能出席
        kk = nex[kk];
    }
    dp[1][d] += rating[d];///出席需要加上rating
}
int main()
{
    while(~scanf("%d",&n))
    {
        for(int i = 1;i <= n;i ++)
            scanf("%d",&rating[i]);
        memset(fir,-1,sizeof(fir));
        memset(dp,0,sizeof(dp));
        int i = 0;
        while(~scanf("%d%d",&l[i],&k[i]) && l[i] && k[i])
        {
            vis[l[i]] = 1;
            nex[i] = fir[k[i]];
            fir[k[i]] = i;
            i ++;
        }
        for(i = 1;i <= n;i ++)
        {
            if(!vis[i])
            {
                dfs(i);
                cout<<max(dp[0][i],dp[1][i])<<endl;
            }
            vis[i] = 0;
        }
    }
}