UVA 11827 - Maximum GCD

/***
	Md. Nazmul Hasan
	Shahjalal University of Science & Technology,Sylhet.
	hasan08sust@gmail.com
	***/
	#include<iostream>
	#include<cstdio>
	#include<stack>
	#include<queue>
	#include<map>
	#include<vector>
	#include<algorithm>
	#include<cstring>
	#include<sstream>
	#include<cmath>
	#include <iomanip>
	using namespace std ;
	typedef long long ll ;
	typedef int in ;
	typedef unsigned long long ull ;
	const double pi = 2*acos(0) ;
	#define maxi 40000
	#define pf printf
	#define sc scanf
	#define pb push_back
	#define MEM(x,y) (memset((x),(y),sizeof(x)))
	#define MIN(x,y) ((x) < (y) ? (x) : (y))
	#define MAX(x,y) ((x) > (y) ? (x) : (y))
	#define load(array,size) for(int i=0 ; i<size ; i++) cin>>array[i] ;
	#define new_line pf("\n")
	#define clear_data(array) memset(array,0,sizeof(array))
	#define highest_int 2147483647
	int GCD(int a, int b)
	{
	if(a%b==0) return b;
	return GCD(b,a%b);
	}
	int main()
	{
	int test,p,mx,a,b,val;
	string str;
	vector<int>data;
	sc("%d",&test);
	getchar();
	while(test--)
	{
	getline(cin,str);
	stringstream ss(str);
	while(ss>>p)
	{
	data.pb(p);
	}
	mx =0 ;
	for(int i=0 ; i<data.size()-1 ; i++)
	{
	for(int j=i+1 ; j<data.size() ; j++)
	{
	a = data[i];
	b = data[j];
	val = GCD(a,b);
	//pf("GCD OF %d & %d is %d\n",a,b,val);
	if(mx<val)
	{
	mx = val;
	}
	}
	}
	pf("%d\n",mx);
	data.clear();
	}
	return 0;
	}