UVa 11827 - Maximum GCD

#include<bits/stdc++.h>

using namespace std;

int gcd(int a, int b)
{
 
 if(a%b==0) return b;
 return gcd(b,a%b);
}

int main()
{
 
 int tc,N,a[99],ans;
 string s;
 
 while(cin>>tc)
 {
  getchar();
 while(tc--){
  
  N=0;
  ans=0;
  
  getline(cin,s);
  istringstream is(s);
 
  
  while(is>>a[N]){
    ++N;
  }
  
  for(int i = 0;i<N;++i)
   for(int j = i+1;j<N;++j)
    ans = max(ans,gcd(a[i],a[j]));
  
  cout<<ans<<endl;
 }
 }
 
 
 
 return 0;
}