another simple approach might be that we find product of first 7 natural numbers. now iterate through array and if current_element <= 7 then product /= current_element and check if product == 1 then res = i+1.
this solution is working fine but let me know if there is any case where this might cause problem.
#include <bits/stdc++.h>
#include <iostream>
using namespace std;
ll fact(ll n) { if( n<=1 ) return n; return n * fact(n-1); }
int main() {
// your code goes here
int t;
cin>>t;
while(t--){
int n,tmp,product=1,res;
cin>>n;
product = fact(7);
for(int i=0;i<n;i++){
cin>>tmp;
if(tmp <= 7){
product /= tmp;
if(product == 1)
res = i+1;
}
}
cout<<res<<endl;
}
return 0;
}