P1195 口袋的天空

#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
#define tcl(a,b,c) for(a=b;a<=c;a++)
const int maxx=20001;
struct data
{
    int x,y,dis;
}a[100001];
int f[maxx];
int getf(int x)
{
    if(f[x]==x) return x;
    else f[x]=getf(f[x]);
    return f[x];
}
bool cmp(data a,data b)
{
    return a.dis<b.dis;
}
int n,m,k,sum,ans;
int main()
{
    int i;
    cin>>n>>m>>k;
    tcl(i,1,n)
    {
        f[i]=i;
    }
    tcl(i,1,m)
    {
        cin>>a[i].x>>a[i].y>>a[i].dis;
    }
    sort(a+1,a+1+m,cmp);
    tcl(i,1,m)
    {
        if(getf(a[i].x)!=getf(a[i].y))
        {
            f[getf(a[i].x)]=getf(a[i].y);
            ans+=a[i].dis;
            sum++;
        }
        if(sum==n-k)//K个树已经建成
        {
            cout<<ans<<endl;
            return 0;
        }
    }
    cout<<"No Answer"<<endl;
    return 0;
}