性质

• 1.$gcd(a,b)=gcd(b,a\%b)$;
• 2.$gcd(a,0)=a$

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

int n;

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

int main()
{
    cin>>n;
    while (n -- )
    {
        int a,b;
        cin>>a>>b;
        cout<<gcd(a,b)<<endl;
    }
}