BC 1002 (放代码)

/************************************************
* Author        :Running_Time
* Created Time  :2015-9-5 19:48:28
* File Name     :B.cpp
 ************************************************/

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <bitset>
#include <cstdlib>
#include <ctime>
using namespace std;

#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
typedef long long ll;
const int N = 5e4 + 10;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
int a[110];
map<int, int> cnt;

void factorize(int n)  {
    for (int i=2; i*i<=n; ++i)    {
        while (n % i == 0)  {
            n /= i;
            cnt[i]++;
        }
    }
    if (n != 1) cnt[n]++;
}

int main(void)    {
	int T;	scanf ("%d", &T);
	while (T--)	{
        cnt.clear ();
		int n;	scanf ("%d", &n);
		for (int i=1; i<=n; ++i)	{
			scanf ("%d", &a[i]);
		}
		for (int i=1; i<=n; ++i)	{
			factorize (a[i]);
		}
        map<int, int>::iterator it;
        vector<int> ans;
        for (it=cnt.begin (); it!=cnt.end (); ++it) {
            if (it->second)   {
                for (int i=1; i<=it->second; ++i)    {
                    ans.push_back (it->first);
                    if (ans.size () == 2)   break;
                }
            }
            if (ans.size () == 2)   break;
        }
        if (ans.size () != 2)   puts ("-1");
        else    {
            printf ("%I64d\n", ans[0] * 1ll * ans[1]);
        }
	}

    return 0;
}