```cpp
#include<bits/stdc++.h>
using namespace std;
int l[200010],r[200010],sum1,sum0,ans,n;
int main()
{
cin>>n;
for (int i=1;i<=n;i++){
int x; cin>>x;
sum1+=(x==1), sum0+=(x==0);
int t=sum0-sum1+n;
if (!l[t]&&t!=n) l[t]=i; else r[t]=i;
}
for (int i=0;i<=2*n;i++) ans=max(ans,r[i]-l[i]);
cout<<ans<<endl;
return 0;
}
```
by liuzhuoran141516 @ 2024-07-21 19:53:22
试一下
by liuzhuoran141516 @ 2024-07-21 19:53:52
@[liuzhuoran141516](/user/1351155) 好眼熟
by wuyu6688 @ 2024-08-01 22:07:08