gg，y一下就是每个点到根的距离用rank维护，，

#include 
  
   
#include 
   
     #include 
    
      #include 
     
       #include 
      
        #include 
       
         #include 
        
          #include 
         
           using namespace std; #define mod 1000000007 #define ll int #define rank Rank #define N 100100 ll n; ll f[N], rank[N]; ll find(ll x){ if(x==f[x]) return x; int t = f[x]; f[x] = find(f[x]); rank[x] += rank[t]; return f[x]; } bool Union(int x, int y, int m){ int fx = find(x), fy = find(y); if(fx==fy) { if(rank[x] + m != rank[y]) return false; return true; } f[fy] = fx; rank[fy] = rank[x] + m -rank[y]; return true; } void init(){ for(int i = 0; i <= n; i++) f[i] = i, rank[i] = 0; } int main(){ int i, j, u, v, d, que; while(~scanf("%d %d",&n,&que)) { init(); int ans = 0; while(que--) { scanf("%d %d %d",&u,&v,&d); if(Union(u,v,d)==false) ans++; } cout<