hdu3047
题解:带权并查集裸题
#include <bits/stdc++.h>
using namespace std;
int const N = 50000 + 10;
int n,m,a,b,x,f[N],val[N];
int find(int x){
if(x != f[x]){
int t = f[x];
f[x] = find(f[x]);
val[x] += val[t];
}
return f[x];
}
int main(){
ios::sync_with_stdio(false);
while(cin>>n>>m){
int ans = 0;
for(int i=0;i<=n;i++) f[i] = i,val[i] = 0;
for(int i=1;i<=m;i++){
cin>>a>>b>>x; //b编号比a大x
int fa = find(a), fb = find(b);
if(fa != fb){
f[fb] = fa;
val[fb] = val[a] + x - val[b];
}else if(val[b] - val[a] != x) ans++;
}
cout<<ans<<endl;
}
return 0;
}