Almost All Divisors（求因子个数及思维）

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<queue>
#include<stack>
#include<set>
#include<vector>
#include<map>
#include<cmath>
const int maxn=1e5+5;
typedef long long ll;
using namespace std;
ll count(ll n){
    ll s=1;
    for(ll i=2;i*i<=n;i++){
        if(n%i==0){
            int a=0;
            while(n%i==0){
                n/=i;
                a++;
            }
            s=s*(a+1);
        }
    }
    if(n>1) s=s*2;
    return s;
}
ll a[maxn];
int main()
{
   int T;
   cin>>T;
   int n;
   while(T--)
   {
       scanf("%d",&n);
       ll maxx=2;
       ll minn=10000000;
       ll x;
       for(int t=0;t<n;t++)
       {
           scanf("%lld",&a[t]);
           maxx=max(a[t],maxx);
           minn=min(a[t],minn);
    }
    ll ans=maxx*minn;
    bool flag=false;
    for(int t=0;t<n;t++)
    {
        if(ans%a[t]!=0)
        {
            flag=true;
        }
    }
    if(count(ans)-2==n&&flag==false)
    printf("%lld\n",ans);
    else
    {
        printf("-1\n");
    }
    

   }
   return 0;
}