946B - Weird Subtraction Process - CodeForces Solution

#include<bits/stdc++.h>
#define ll long long
#define rep(i,a,b) for(int i=a;i<b;i++)
#define vi vector<int>
using namespace std;
int main() {
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll a, b;
    cin >> a >> b ;
    while (a > 0 && b > 0 ) {
        if (a >= 2 * b)
        {
            a %= 2 * b;
        }
        else if (b >= 2 * a)
        {
            b %= 2 * a;
        }
        else {
            break;
        }
    }
    cout << a << " " << b << endl;
    return 0;
}