poj 2492 A Bug's Life

#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
const int M = 2e3+7;
int _,n,m,cas=1;
int f[M],cnt[M];
void init(){
    for(int i=0;i<=n;i++) f[i]=i,cnt[i]=0;
}
int find(int x){
    if(x==f[x]) return x;
    int tmp=f[x];
    f[x]=find(f[x]);
    cnt[x]=(cnt[x]+cnt[tmp])%2;
    return f[x];
}
int main(){
    freopen("1.in","r",stdin);
    freopen("1.out","w",stdout);
    scanf("%d",&_);
    while(_--){
        scanf("%d%d",&n,&m);
        init();
        int flg=1;
        while(m--){
            int u,v;
            scanf("%d%d",&u,&v);
            if(u<v) swap(u,v);
            int fu=find(u),fv=find(v);
            if(fu==fv){
                if((cnt[u]-cnt[v]+2)%2!=1) flg=0;
            }
            else{
                f[fu]=fv;
                cnt[fu]=(cnt[v]-cnt[u]+1+2)%2;
            }
        }
        printf("Scenario #%d:\n",cas++);
        if(flg) printf("No suspicious bugs found!\n\n");
        else printf("Suspicious bugs found!\n\n");
    }
    return 0;
}