1 #include<cstdio> 2 #include<cstring> 3 #include<algorithm> 4 int main() { 5     int n; 6     scanf("%d",&n); 7     int t[n+1],w[n+1],s[n+1]; 8     memset(s,0,sizeof s); 9     for(int i=1;i<=n;i++) scanf("%d",&t[i]);10     int ans=0x7fffffff;11     for(int i=1;i<=n;i++) {12         int cnt=0,p;13         for(p=i;!s[p];p=t[p]) {14             s[p]=i;15             w[p]=cnt++;16         }17         if(s[p]==i) ans=std::min(ans,cnt-w[p]);18     }19     printf("%d\n",ans);20     return 0;21 }