```cpp
else if(x==0&&y==0){//当输出双0时，判断并输出
if(book==0)
cout<<1<<endl;//未出现环路
else
cout<<0<<endl;//出现环路
continue;
}
```
@[libin13815498262](https://www.luogu.com.cn/user/922071)
这里有问题，因为要初始化。改进后如下：
```cpp
else if(x==0&&y==0){
if(book==0)
cout<<1<<endl;
else
cout<<0<<endl;
//初始化
book=0;
for(int i=1;i<=10000;i++)
fa[i]=i;
continue;
}
by xiaoshumiao @ 2023-10-30 16:08:03
抱歉，是
```
pre[i]=i;
```
by xiaoshumiao @ 2023-10-30 16:08:54