zoj3659

Posted 2021-01-14 zsben991126

#include<iostream>
#include<algorithm>
#include<cstring>
#define ll long long 
#include<cstdio>
#define MAXN 200005 
using namespace std;
int F[MAXN];
int num[MAXN];
ll s[MAXN];
struct Edge{
    int a,b,cost;
}e[MAXN];
int cmp(Edge &a,Edge &b){
    return a.cost>b.cost;
}
int find(int x){
    if(F[x]==-1) return x;
    return F[x]=find(F[x]);
}
int main(){
    int n;
    while(scanf("%d",&n)==1){
        for(int i=1;i<=n;i++){
            F[i]=-1;
            num[i]=1;
            s[i]=0;
        }
        for(int i=0;i<n-1;i++)
            scanf("%d%d%d",&e[i].a,&e[i].b,&e[i].cost);
        sort(e,e+n-1,cmp);
        
        //手动合并 
        int t1,t2;
        for(int i=0;i<n-1;i++){
            t1=find(e[i].a);
            t2=find(e[i].b);
            if(t1!=t2){
                s[t2]=max((ll)s[t1]+(ll)e[i].cost*num[t2],(ll)s[t2]+(ll)e[i].cost*num[t1]);
                num[t2]+=num[t1];
                F[t1]=t2;
            }
        }
        printf("%lld
",s[t2]);
    }
    return 0;
}