NOIP2014聯合權值

暴力
找中點
累加

int n,f[200010],ansmax,ans;
vector<int>t[200010];
int main(){
    n=read();
    fr(i,1,n-1)
    {
        int u=read(),v=read();
        t[u].push_back(v);
        t[v].push_back(u);
    }
    fr(i,1,n)
        f[i]=read();
    fr(i,1,n)
    {
        int max1=0,max2=0,sum=0;
        fr(j,0,t[i].size()-1)
        {
            int k=f[t[i][j]];
            sum=(sum+k)%mod;
            if(k>max1)
            {
                max2=max1;
                max1=k;
            }
            else
                if(k>max2)
                    max2=k;
        }
        ansmax=max(ansmax,max1*max2);
        fr(j,0,t[i].size()-1)
        {
            int k=f[t[i][j]];
            ans=(ans+(k*(sum-k+mod))%mod)%mod;
        }
    }
    printf("%d %d\n",ansmax,ans);
    rt 0;
}