[CCF CSP]数据中心2018-12-4

题目链接:http://118.190.20.162/view.page?gpid=T83

#include <iostream>
#include <algorithm>
using namespace std;
const int N=5*100000+10;
int father[N];
struct node{
    int u,v;
    int weight;
}E[N];
int find(int x){
    return x==father[x]?x:father[x]=find(father[x]);
}
void merge(int x,int y){
    int xx=find(x);
    int yy=find(y);
    if(xx!=yy){
        father[xx]=yy;
        return ;
    }
}
int n,m,root;
int max_val=-1;
bool cmp(node a,node b){
    return a.weight<b.weight;
}
int main() {
    cin>>n>>m>>root;
    for(int i=1;i<=n;i++){
        father[i]=i;
    }
    for(int i=0;i<m;i++){
       cin>>E[i].u>>E[i].v>>E[i].weight;
    }
    int num=0;
    sort(E,E+m,cmp);
    for(int i=0;i<m;i++){
        int x=find(E[i].u);
        int y=find(E[i].v);

        if(x!=y){
            num++;
            merge(E[i].u,E[i].v);
            max_val=max(max_val,E[i].weight);
        }
        if(num==n-1){
            break;
        }
    }
    cout<<max_val<<endl;
    return 0;
}