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Re: Question about `list.insert`

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Date Fri, 7 Feb 2014 14:20:43 +1100
Subject Re: Question about `list.insert`
From Chris Angelico <rosuav@gmail.com>
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On Fri, Feb 7, 2014 at 2:11 PM, Tim Chase <python.list@tim.thechases.com> wrote:
> On 2014-02-06 22:00, Roy Smith wrote:
>> > list does not promise better than O(1) behavior
>>
>> I'm not aware of any list implementations, in any language, that
>> promises better than O(1) behavior for any operations.  Perhaps
>> there is O(j), where you just imagine the operation was performed?
>
> Pish...there's always O(0) which is achieved by *not* performing some
> unneeded operation ;-)
>
> -tkc

Ooh! Ooh! I got it!

class fast_list(list):
    def append(self,obj,randrange=random.randrange):
        if len(self) and randrange(len(self)): return
        return super().append(obj)

Repeated appends to this list are amortized O(0)!

ChrisA

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Thread

Question about `list.insert` cool-RR <ram.rachum@gmail.com> - 2014-02-06 15:59 -0800
  Re: Question about `list.insert` Terry Reedy <tjreedy@udel.edu> - 2014-02-06 19:40 -0500
  Re: Question about `list.insert` MRAB <python@mrabarnett.plus.com> - 2014-02-07 00:42 +0000
  Re: Question about `list.insert` Terry Reedy <tjreedy@udel.edu> - 2014-02-06 21:48 -0500
  Re:Question about `list.insert` Dave Angel <davea@davea.name> - 2014-02-06 21:54 -0500
    Re: Question about `list.insert` Roy Smith <roy@panix.com> - 2014-02-06 22:00 -0500
      Re: Question about `list.insert` Rustom Mody <rustompmody@gmail.com> - 2014-02-06 19:08 -0800
      Re: Question about `list.insert` Tim Chase <python.list@tim.thechases.com> - 2014-02-06 21:11 -0600
        Re: Question about `list.insert` Roy Smith <roy@panix.com> - 2014-02-06 22:12 -0500
          Re: Question about `list.insert` Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-02-07 17:18 +1300
      Re: Question about `list.insert` Chris Angelico <rosuav@gmail.com> - 2014-02-07 14:14 +1100
      Re: Question about `list.insert` Chris Angelico <rosuav@gmail.com> - 2014-02-07 14:20 +1100
        Re: Question about `list.insert` Rustom Mody <rustompmody@gmail.com> - 2014-02-06 19:29 -0800
          Re: Question about `list.insert` Chris Angelico <rosuav@gmail.com> - 2014-02-07 14:45 +1100
      Re: Question about `list.insert` Asaf Las <roegltd@gmail.com> - 2014-02-06 19:28 -0800
  Re: Question about `list.insert` Dan Stromberg <drsalists@gmail.com> - 2014-02-06 20:52 -0800
    Re: Question about `list.insert` Asaf Las <roegltd@gmail.com> - 2014-02-06 21:18 -0800
  Re: Question about `list.insert` Peter Otten <__peter__@web.de> - 2014-02-07 09:25 +0100

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