样例错了
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<string>
#include<map>
#include<vector>
#include<cmath>
#include<cstdlib>
#include<list>
#include<queue>
#define mm(a,b) memset(a,b,sizeof(a))
#define ACCELERATE (ios::sync_with_stdio(false),cin.tie(0))
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
#define MAXNL 0x3fffffff
#define MAXN 0x3f3f3f3f
using namespace std;
//#define debug
struct node{
int u,v,w;
};
bool cmp(const node& a,const node& b){
return a.w<b.w;
}
int fa[1005];
int get_father(int x){
return fa[x]=fa[x]==x?x:get_father(fa[x]);
}
int main()
{
#ifdef debug
freopen("in.txt","r",stdin);
freopen("out.txt","w",stdout);
#endif // debug
node mmp[15005];
node p[15005];
int n,m;
while(scanf("%d%d",&n,&m)!=EOF){
for(int i=0;i<m;i++){
scanf("%d%d%d",&mmp[i].u,&mmp[i].v,&mmp[i].w);
}
sort(mmp,mmp+m,cmp);
int maxn=-1;
int ans=0;
for(int i=1;i<=n;i++) fa[i]=i;
int cnt=0;
for(int i=0;i<m;i++){
if(get_father(mmp[i].u)!=get_father(mmp[i].v)){
ans+=mmp[i].w;
fa[fa[mmp[i].u]]=fa[mmp[i].v];
p[cnt].u=mmp[i].u,p[cnt].v=mmp[i].v;
cnt++;
if(cnt==n-1){
maxn=mmp[i].w;
break;
}
}
}
printf("%d\n",maxn);
printf("%d\n",cnt);
for(int i=0;i<cnt;i++){
printf("%d %d\n",p[i].u,p[i].v);
}
}
return 0;
}