COMPLEJIDAD POSTORDEN

                                                                                //O(1)
    public Iterator<T> postOrden(){                                             //T= 2+2+2 = 6
        ListaCD<T> l=new ListaCD<T>();                                          //2
        postOrden(this.getRaiz(),l);                                          //2
        return (l.iterator());                                                  //2
    }
T= 2+2+2 = 6

T=6

O(1)