HDU6025

Coprime Sequence

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)
Total Submission(s): 606    Accepted Submission(s): 305

Problem Description

Do you know what is called ``Coprime Sequence''? That is a sequence consists of  n positive integers, and the GCD (Greatest Common Divisor) of them is equal to 1.
``Coprime Sequence'' is easy to find because of its restriction. But we can try to maximize the GCD of these integers by removing exactly one integer. Now given a sequence, please maximize the GCD of its elements.

 

Input

The first line of the input contains an integer  T(1≤T≤10), denoting the number of test cases.
In each test case, there is an integer  n(3≤n≤100000) in the first line, denoting the number of integers in the sequence.
Then the following line consists of  n integers  a1,a2,...,an(1≤ai≤109), denoting the elements in the sequence.

 

Output

For each test case, print a single line containing a single integer, denoting the maximum GCD.

 

Sample Input

3 3 1 1 1 5 2 2 2 3 2 4 1 2 4 8

 

Sample Output

1 2 2

 

#include
#include
#define N 100010
using namespace std;
int gcd(int a,int b)
{
    while(b!=0)
    {
        int c=a%b;
            a=b;
            b=c;
    }
    return a;
}
int main()
{
    int T,n,i,j,a[N],fro[N],beh[N],ans;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d",&n);
        for(i=0;i=0;i--)
        {
            beh[i]=gcd(beh[i+1],a[i]);//求后缀GCD
        }
        ans=0;
        for(i=0;i