//Max ones in array
#include<bits/stdc++.h>
using namespace std;
int main()
{
//code
int tc;cin>>tc;
while(tc--){
int n;cin>>n;
int arr[n],a;
int max_len=-1,cur_len=-1,sum=0;
for(int i=0;i<n;i++){
cin>>a;
if(a==0)
arr[i]=1;
else
arr[i]=0;
}
int start_index=0,j=0,one_idx;
while(j<n){
sum=sum+arr[j];
if(sum<=1){
cur_len++;
if(arr[j]==1){
one_idx=j;
}
}
else{
if(cur_len>max_len){
max_len=cur_len;
cur_len=0;
}
sum--;
j=one_idx;
}
j++;
}
}
return 0;
}
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