O(logn)

C++ 代码

#include<iostream>

using namespace std;

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

int main()
{
    int n;
    cin>>n;
    while(n--){
        int a,b;
        cin>>a>>b;
        cout<<gcd(a,b)<<"\n";
    }
    return 0;
}