poj 2492（并查集）

#include<cstdio>
#include<iostream>
using namespace std;
#define MAXN 2010
int father[MAXN];
int rank[MAXN];
void make_set(int x)
{
    father[x]=x;
    rank[x]=0;
}
int find_set(int x)
{
    int t;
    if(x==father[x]) return x;
    else 
    {
        t=father[x];
        father[x]=find_set(father[x]);
        rank[x]=(rank[x]+rank[t])%2;
        return father[x];
    }
}
void union_set(int x,int y)
{
    int rx=find_set(x);
    int ry=find_set(y);
    father[rx]=ry;
    rank[rx]=(rank[y]-rank[x]+2+1)%2;

}
int main()
{
    int T;
    scanf("%d",&T);
    int n,m;
    for(int t=1;t<=T;t++)
    {        
        scanf("%d%d",&n,&m);
        for(int i=1;i<=n;i++)
            make_set(i);
        int ok=0;
        int a,b;
        for(int i=1;i<=m;i++)
        {
            scanf("%d%d",&a,&b);
            if(ok==1) continue;
            int ra=find_set(a);
            int rb=find_set(b);
            if(ra==rb)
            {
                if((rank[b]-rank[a]+2)%2==0) 
                    ok=1;
            }
            else 
            union_set(a,b);
        }
        printf("Scenario #%d:\n",t);
        if(ok==1) printf("Suspicious bugs found!\n\n");
        else printf("No suspicious bugs found!\n\n");
    }
}