On Thu, 11 Sep 2008 02:23:43 -0700, process wrote:
> Python uses arrays for lists right?
`len()` on `list` objects is O(1).
> def quicksort(lista):
> if lista == []:
> lista
> else:
> return quicksort([x for x in lista[1:] if x < lista[0]]) +
> [lista[0]] + \
> quicksort([x for x in lista[1:] if x >= lista[0]])
>
> or
>
> def quicksort(lista):
> if len(lista) == 0
> lista
> else:
> return quicksort([x for x in lista[1:] if x < lista[0]]) +
> [lista[0]] + \
> quicksort([x for x in lista[1:] if x >= lista[0]])
>
> wait first one raises TypeError unsupported operand types.
Both do because `None` + `list` doesn't make sense. You should actually
``return`` the `lista` in the ``if`` branch instead of just lookup the
object for that name and then do nothing with it.
Shorter alternative:
if not lista:
return []
Empty lists are considered `False` in a boolean test.
Ciao,
Marc 'BlackJack' Rintsch
--
http://mail.python.org/mailman/listinfo/python-list
