Zero Judge a129. 最小生成樹

#include <bits/stdc++.h>
using namespace std;
vector<int> a(100000),size(100000);
struct cmp{
    bool operator()(const array<int,3> &a,const array<int,3> &b){
        return a[2]>b[2];
    }
};
int findroot(int x){
    return x==a[x]? x:(a[x]=findroot(a[x]));
}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int m,n,aroot,broot,tt;
    long long sum;
    array<int,3> temp;
    priority_queue<array<int,3>,vector<array<int,3>>,cmp> path;
    while(cin>>n>>m){
        sum=0;
        for(int i=0;i<n;i++) a[i]=i,size[i]=1;
        for(int i=0;i<m;i++){
            cin>>temp[0]>>temp[1]>>temp[2];
            path.emplace(temp);
        }
        while(!path.empty()){
            temp=path.top();
            path.pop();
            aroot=findroot(temp[0]);
            broot=findroot(temp[1]);
            if(aroot==broot) continue;
            if(size[aroot]<size[broot]) swap(aroot,broot);
            size[aroot]+=size[broot];
            a[broot]=aroot;
            sum+=temp[2];
        }
        aroot=findroot(0);
        if(size[aroot]==n) cout<<sum<<'\n'; else cout<<"-1\n";
    }
    return 0;
}
/*
Zero Judge a129. 最小生成樹
https://zerojudge.tw/ShowProblem?problemid=a129
2024 June 16
AC (0.4s, 6.4MB)
*/