HDU3560 Graph’s Cycle Component

#include<iostream>#include<cstdio>#include<cmath>#include<cstring>#include<string>#include<algorithm>#include<memory.h>#include<queue>#include<stack>#define N 100002int n,m,pre[N],flag[N],degree[N];void clear(){for(int i=0;i<n;i++){degree[i]=flag[i]=0;pre[i]=i;}}int main(){int i;int a,b,t1,tt1,t2,tt2,f1,f2;int ans1,ans2;while(scanf("%d%d",&n,&m),n+m){clear();while(m--){scanf("%d%d",&a,&b);degree[a]++;degree[b]++;f1=pre[a];f2=pre[b];while(pre[f1]!=f1)f1=pre[f1];while(pre[f2]!=f2)f2=pre[f2];t1=a;t2=b;while(pre[t1]!=f1){tt1=pre[t1];pre[t1]=f1;}while(pre[t2]!=f2){tt2=pre[t2];pre[t2]=f2;}if(f1==f2)continue;pre[f1]=pre[f2];}ans1=ans2=0;for(i=0;i<n;i++){f1=pre[i];while(pre[f1]!=f1)f1=pre[f1];t1=i;while(pre[t1]!=f1){tt1=pre[t1];pre[t1]=f1;t1=tt1;}if(degree[i]!=2)flag[f1]=1;}for(i=0;i<n;i++){if(pre[i]!=i)continue;ans1++;if(!flag[i])ans2++;}printf("%d %d\n",ans1,ans2);}return 0;}