hdu 3047 Zjnu Stadium（并查集）

int n,m;
int fa[50005];
int dis[50005];


int findFa(int x){
    if(fa[x]==x)
        return fa[x];
    int t=findFa(fa[x]);
    dis[x]+=dis[fa[x]];
    return fa[x]=t;
}

int main(){

    while(scanf("%d%d",&n,&m)!=EOF){
        rep(i,0,n-1){
            fa[i]=i;
            dis[i]=0;
        }

        int ans=0;
        while(m--){
            int a,b,x;
            scanf("%d%d%d",&a,&b,&x);
            int faa=findFa(a);
            int fbb=findFa(b);
            if(faa!=fbb){
                fa[fbb]=faa;
                dis[fbb]=dis[a]+x-dis[b];
            }else{
                if((dis[fbb]%300)!=((dis[a]+x-dis[b])%300)){
                    ++ans;
                }
            }
        }
        printf("%d\n",ans);
    }

    return 0;
}