B

B - Networking

思路：并查集板子。

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int fa[60];
int n,m,tot,sum;
struct nond{
    int x,y,z;
}v[2600];
int cmp(nond a,nond b){
    return a.z<b.z;
}
int find(int x){
    if(fa[x]==x)    return x;
    else return fa[x]=find(fa[x]);
}
int main(){
    while(scanf("%d%d",&n,&m)&&n){
        for(int i=1;i<=m;i++)
            scanf("%d%d%d",&v[i].x,&v[i].y,&v[i].z);
        sort(v+1,v+1+m,cmp);
        for(int i=1;i<=n;i++)    fa[i]=i;
        for(int i=1;i<=m;i++){
            int dx=find(v[i].x);
            int dy=find(v[i].y);
            if(dx==dy)    continue;
            tot++;
            fa[dy]=dx;
            sum+=v[i].z;
            if(tot==n-1)    break;    
        }
        cout<<sum<<endl;sum=0;tot=0;
    }
}