题解：最大生成树加判环……
#include <cstdio>
#include <algorithm>
using namespace std;
struct node{int a,b,l;}seg[100005];
bool cmp(node a,node b){return a.l>b.l;}
int ans,m,n,f[10005],mark[10005];
int sf(int x){return f[x]==x?x:f[x]=sf(f[x]);}
int main(){
while(scanf("%d%d",&n,&m)){
if (m==0&&n==0)break; ans=0;
for(int i=0;i<n;i++)f[i]=i,mark[i]=0;
for(int i=0;i<m;i++)scanf("%d%d%d",&seg[i].a,&seg[i].b,&seg[i].l);
sort(seg,seg+m,cmp);
for(int i=0;i<m;i++){
int q=sf(seg[i].a),w=sf(seg[i].b);
if(q==w){
if(mark[q]==0&&mark[w]==0) ans+=seg[i].l,mark[q]=1;
continue;
}else{
if(mark[q]==1&&mark[w]==1)continue;
if(mark[q]==1||mark[w]==1)ans+=seg[i].l,f[q]=w,mark[w]=1;
else f[q]=w,ans+=seg[i].l;
}
}
printf("%d
",ans);
}
return 0;
}