可以证明所有可能的边都要+1

#include
     
      #include
      
       #include
       
        const int maxn = 400100;int fa[maxn];int n,m;struct T{    int x,y,v;    inline int operator <(const T&b)const{        return v
        
         > n >> m;    for(int i=1;i<=n;++i)fa[i]=i;    for(int i=1;i<=m;++i)std::cin >> way[i].x >> way[i].y >> way[i].v;    std::sort(way+1,way+m+1);    int ans=0;    for(int i=1;i<=m;++i){        for(int j=i;j<=m && way[j].v==way[i].v;++j)ans+=find(way[j].x)!=find(way[j].y);        for(int j=i;j<=m && way[j].v==way[i].v;++j){            if(find(way[j].x)!=find(way[j].y))                fa[find(way[j].x)]=find(way[j].y);            i=j;        }    }    std::cout << ans - n + 1 << '\n';}