Almost All Divisors

https://codeforces.com/contest/1165/problem/D

题解：给定的数组是答案的除1和本身以外所有因子，求答案

题解：贪心

答案=最大值*最小值

因子可能有多或者少；

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
#define endl "\n"
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=100000+10;
const int M=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,p,l,r,u,v;
ll ans,cnt,flag,temp,sum;
ll a[N];
char str;
struct node{};
int main()
{
#ifdef DEBUGfreopen("input.in", "r", stdin);//freopen("output.out", "w", stdout);
#endif//ios::sync_with_stdio(false);//cin.tie(0);//cout.tie(0);scanf("%d",&t);while(t--){scanf("%d",&n);ll maxl=-INF;ll minl=INF;for(int i=1;i<=n;i++){scanf("%I64d",&a[i]);maxl=max(a[i],maxl);minl=min(a[i],minl);}ans=maxl*minl;sort(a+1,a+n+1);int sqr=sqrt(ans);cnt=0;for(int i=2;i<=sqr;i++){if(ans%i==0){int x=lower_bound(a+1,a+n+1,ans/i)-a;int y=lower_bound(a+1,a+n+1,i)-a;//cout<<x<<endl;if(x>n||x<1||y>n||y<1||a[x]!=ans/i||a[y]!=i){ans=-1;break;}cnt++;if((ll)i*i!=ans){cnt++;}}}cout<<(cnt==n?ans:-1)<<endl;}#ifdef DEBUGprintf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC);
#endif//cout << "Hello world!" << endl;return 0;
}

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