70分求助

#include<bits/stdc++.h>

using namespace std;
int n,ans=2,a[100001],na[100001],wo[100001],z[100001],ansl,w,w1;
map<int,int>q;
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		na[i]=na[i-1];wo[i]=wo[i-1];
		if(a[i])na[i]+=1;
		else wo[i]+=1;
		z[i]=na[i]-wo[i];
		if(!q[z[i]])q[z[i]]=i;
		else ans=max(ans,i-q[z[i]]);
		
	}
	cout<<ans<<endl;
	//for(int i=1;i<=n;i++)cout<<i<<' '<<z[i]<<'\n';
	return 0;
}