GCD, LCM and Euclidean Algorithm Extended

ll get_gcd(ll a, ll b) { 
   if (b == 0) 
      return a; 
   return get_gcd(b, a % b);  
} 
ll get_lcm(ll a, ll b) {
    return a / get_gcd(a, b) * b;
}

ll gcdExtended(ll a, ll b, ll *x, ll *y) 
{ 
    if (a == 0) { 
        *x = 0; 
        *y = 1; 
        return b; 
    } 
  
    ll x1, y1; 
    ll gcd = gcdExtended(b%a, a, &x1, &y1); 
  
    *x = y1 - (b/a) * x1; 
    *y = x1; 
  
    return gcd; 
}