带权并查集，设f[x]为x的父亲，s[x]为sum[x]-sum[fx]，路径压缩的时候记得改s

#include
    
     #include
     
      using namespace std;const int N=200005;int n,m,s[N],f[N],ans;int read(){    int r=0,f=1;    char p=getchar();    while(p>'9'||p<'0')    {        if(p=='-')            f=-1;        p=getchar();    }    while(p>='0'&&p<='9')    {        r=r*10+p-48;        p=getchar();    }    return r*f;}int zhao(int x){    if(f[x]==x)        return x;    int nw=zhao(f[x]);    s[x]+=s[f[x]];    return f[x]=nw;}int main(){    while(~scanf("%d%d",&n,&m))    {        for(int i=0;i<=n;i++)            f[i]=i,s[i]=0;        ans=0;        while(m--)        {            int x=read()-1,y=read(),z=read(),fx=zhao(x),fy=zhao(y);            if(fx!=fy)            {                f[fy]=fx;                s[fy]=s[x]-s[y]+z;            }            else if(s[y]-s[x]!=z)                ans++;        }        printf("%d\n",ans);    }    return 0;}