poj 1182 (扩展并查集)

#include <stdio.h>
#include <algorithm>
#include <string.h>
using namespace std;
const int N =50010;
int father[N];
int relation[N];  ///relation[] 为0表示同类 1表示被根节点吃 2表示吃根节点

int _find(int x){
    if(x!=father[x]){
        int t = father[x];
        father[x] = _find(father[x]);
        relation[x]=(relation[x]+relation[t])%3; ///对3取余防止出现大于2的情况
    }
    return father[x];
}
int main()
{
    int n,m;
    while(scanf("%d%d",&n,&m)!=EOF){
        for(int i=0;i<=n;i++){
            father[i] = i;
            relation[i] = 0;  ///自己与自己当然是同类
        }
        int ans = 0;
        while(m--){
            int d,a,b;
            scanf("%d%d%d",&d,&a,&b);
            if(a>n||b>n||(a==b)&&(d==2)) {
                ans++;
                continue;
            }
            int roota = _find(a);
            int rootb = _find(b);
            if(roota==rootb){ ///当前结点已经是同一棵数了
                if(d==1&&relation[a]!=relation[b]) ans++; ///相同种类但relation不同
                if(d==2&&relation[a]!=(relation[b]+2)%3) ans++;
            }else{
                father[rootb] = roota;
                relation[rootb] = (relation[a]+(d-1)-relation[b]+3)%3;
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}