Barn （2012 acm-icpc 长春邀请赛 K题 ）树型dp

比赛时调试了半天没A掉，妹子的！！！又打铁了，现在补一下，不知是否正确

#include<iostream>
#include<cstring>
#include <cstdio>
#include<string>
#include<queue>
#include<vector>
#include<map>
#include <set>
#include<ctime>
#include<cmath>
#include <cstdlib>
#include<algorithm>
using namespace std;
#define LL long long
const LL N=10000+10;
const LL INF=INT_MAX;
vector< pair<LL,LL> > G[N];
bool vis[N];
LL c[N],x[N],low[N],sum[N];
LL rsum[N],up[N];
LL root=0;
void dfs1(LL u){
    vis[u]=1;
    for(LL i=0;i<G[u].size();i++){
        LL v=G[u][i].first,w=G[u][i].second;
        if(!vis[v]){
            dfs1(v);
            low[u]+=low[v];
            sum[u]+=sum[v]+low[v]*w;
        }
    }
    low[u]+=x[u];
}
void dfs2(LL u){
    vis[u]=1;
    for(LL i=0;i<G[u].size();i++){
        LL v=G[u][i].first,w=G[u][i].second;
        if(!vis[v]){
            up[v]=low[root]-low[v];
            rsum[v]=rsum[u]+sum[u]-sum[v]-low[v]*w+up[v]*w;
            dfs2(v);
        }
    }
}
int main(){
    LL n;
    while(scanf("%lld",&n)!=EOF){
        for(LL i=0;i<n;i++){
            G[i].clear();
        }
        LL sum_num=0;
        for(int i=0;i<n;i++) {
            scanf("%lld",&x[i]);
            sum_num+=x[i];
        }

        for(int i=0;i<n;i++) 
            scanf("%lld",&c[i]);
        for(LL i=0;i<n-1;i++){
            LL u,v,w;
            scanf("%lld%lld%lld",&u,&v,&w);
            G[v].push_back(make_pair(u,w));
            G[u].push_back(make_pair(v,w));
        }
        //cout<<endl;
        //for(LL i=0;i<n;i++){
        //    cout<<i<<" : ";
        //    for(LL j=0;j<G[i].size();j++){
        //        cout<<G[i][j].first<<" "<<G[i][j].second<<" | ";
        //    }
        //    cout<<endl;
        //}
        memset(vis,0,sizeof(vis));
        dfs1(root);
        
        //cout<<endl;
        //for(LL i=0;i<n;i++){
        //    cout<<sum[i]<<endl;
        //}
        memset(vis,0,sizeof(vis));
        dfs2(root);

        //cout<<endl;
        //for(LL i=0;i<n;i++){
        //    cout<<sum[i]<<" "<<rsum[i]<<" "<<low[i]<<" "<<up[i]<<endl;
        //}

        LL ans_id=0,ans_sum=INF;
        for(LL i=0;i<n;i++){
            LL a=rsum[i]+sum[i]+sum_num*c[i];
            if(ans_sum>a){
                ans_id=i;
                ans_sum=a;
            }
        }
        printf("%lld %lld\n",ans_id,ans_sum);
    }
}