public static bool HasCircle(Node<int> lst)
{
    Node<int> curr = lst;
    if(curr == null)
        return false;
    bool flag = false;
    Node<int> temp = lst;
    while(curr != null && !flag)
    {
        while (temp != null && !flag)
        {
            if (temp.GetNext() == curr)
                flag = true;
            temp = temp.GetNext();
        }
        curr = curr.GetNext();
        temp = curr;
    }
    return flag;
}

public static bool HasCircle(Node<int> lst)
{
    Node<int> curr = lst;
    if(curr == null)
        return false;
    bool flag = false;
    Node<int> temp = lst;
    while(curr != null && !flag)
    {
        while (temp != null && !flag)
        {
            if (temp.GetNext() == curr)
                flag = true;
            temp = temp.GetNext();
        }
        curr = curr.GetNext();
        temp = curr;
    }
    return flag;
}