Determine whether given LinkedList is Cyclic or Acyclic

Determine whether given LinkedList is Cyclic or Acyclic

bool determineTermination( Node *head )
{
    Node *fast, *slow;
    fast = slow = head;
    while( true )
    {
        if( !fast || !fast->next )
            return false;
        else if( fast == slow || fast->next == slow )
            return true;
        else
        {
            slow = slow->next;
            fast = fast->next->next;
        }
    }
}