poj 1182 食物链 并查集

#include<iostream>
#include<cstdio>
using namespace std;

 int N,K,relation,a,b,count;
 int p[50010],r[50010];
 void make(){
     for(int i=1;i<=N;i++){
         p[i]=i;
         r[i]=0;
     }
 }
 int find(int x){
     int temp=p[x];
     if(x==p[x])return p[x];
     p[x]=find(p[x]);
     r[x]=(r[x]+r[temp])%3;
     return p[x];
 }
 void unionSet(int x,int y,int px,int py){
     p[px]=py;
     r[px]=(r[y]-r[x]+3+relation-1)%3;
 }
 int main(){
     cin>>N>>K;
     int pa,pb;
     count=0;
     make();
     while(K--){
         scanf("\n%d%d%d",&relation,&a,&b);
         pa=find(a);
         pb=find(b);
         if(a>N||b>N||(relation==2&&a==b)){count++;continue;}
         if(pa!=pb){unionSet(a,b,pa,pb);continue;}
         if((r[a]-r[b]+3)%3!=(relation-1)){count++;continue;}
     }
     cout<<count<<endl;
 }