Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #39362

Re: Python 3.3 vs. MSDOS Basic

Show all headers | View raw

On 02/19/2013 12:31 PM, Ian Kelly wrote:
> On Tue, Feb 19, 2013 at 7:46 AM, Tim Daneliuk <tundra@tundraware.com> wrote:
>> Are you sure you wouldn't like to share with the class?  I'd be interested
>> in seeing your approach...
>
> Very well:
>
> def collatz(n, memo):
>      if n not in memo:
>          if n % 2 == 0:
>              next_n = n // 2
>          else:
>              next_n = 3 * n + 1
>          memo[n] = collatz(next_n, memo) + 1
>      return memo[n]
>
> def run_collatz(upper):
>      table = {1: 0}
>      max_n = max(range(1, upper), key=lambda n: collatz(n, table))
>      return max_n, table[max_n]
>
>>>> run_collatz(1000000)
> (837799, 524)
>
> It could certainly be optimized further, but at about 4 seconds it's
> already fast enough for most purposes.
>

Thanks.  I was specifically curious about your use of dynamic programming.
What about this algorithm makes it particularly an example of this?  Is
it your use of memoization or something other than this?



-- 
-----------------------------------------------------------------------
Tim Daneliuk

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Python 3.3 vs. MSDOS Basic John Immarino <johimm@gmail.com> - 2013-02-18 11:13 -0800
  Re: Python 3.3 vs. MSDOS Basic Chris Angelico <rosuav@gmail.com> - 2013-02-19 08:55 +1100
  Re: Python 3.3 vs. MSDOS Basic Ian Kelly <ian.g.kelly@gmail.com> - 2013-02-18 14:54 -0700
    Re: Python 3.3 vs. MSDOS Basic Tim Daneliuk <tundra@tundraware.com> - 2013-02-19 08:46 -0600
      Re: Python 3.3 vs. MSDOS Basic Ian Kelly <ian.g.kelly@gmail.com> - 2013-02-19 11:31 -0700
        Re: Python 3.3 vs. MSDOS Basic Tim Daneliuk <tundra@tundraware.com> - 2013-02-20 08:21 -0600
          Re: Python 3.3 vs. MSDOS Basic Ian Kelly <ian.g.kelly@gmail.com> - 2013-02-20 11:38 -0700
            Re: Python 3.3 vs. MSDOS Basic Tim Daneliuk <tundra@tundraware.com> - 2013-02-20 16:49 -0600
              Re: Python 3.3 vs. MSDOS Basic Tim Daneliuk <tundra@tundraware.com> - 2013-02-20 16:59 -0600
      Re: Python 3.3 vs. MSDOS Basic Serhiy Storchaka <storchaka@gmail.com> - 2013-02-19 22:28 +0200
      Re: Python 3.3 vs. MSDOS Basic Chris Angelico <rosuav@gmail.com> - 2013-02-20 08:39 +1100
        Re: Python 3.3 vs. MSDOS Basic Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2013-02-20 18:32 +1300
  Re: Python 3.3 vs. MSDOS Basic Chris Angelico <rosuav@gmail.com> - 2013-02-19 08:56 +1100
  Re: Python 3.3 vs. MSDOS Basic Chris Angelico <rosuav@gmail.com> - 2013-02-19 08:58 +1100
    Re: Python 3.3 vs. MSDOS Basic John Immarino <johimm@gmail.com> - 2013-02-18 17:39 -0800
      Re: Python 3.3 vs. MSDOS Basic Chris Angelico <rosuav@gmail.com> - 2013-02-19 14:01 +1100
        Re: Python 3.3 vs. MSDOS Basic Nick Mellor <thebalancepro@gmail.com> - 2013-02-18 20:17 -0800
        Re: Python 3.3 vs. MSDOS Basic Nick Mellor <thebalancepro@gmail.com> - 2013-02-18 20:17 -0800
    Re: Python 3.3 vs. MSDOS Basic John Immarino <johimm@gmail.com> - 2013-02-18 17:39 -0800
      Re: Python 3.3 vs. MSDOS Basic Neil Cerutti <neilc@norwich.edu> - 2013-02-20 17:06 +0000
  Re: Python 3.3 vs. MSDOS Basic Chris Angelico <rosuav@gmail.com> - 2013-02-19 09:01 +1100
  Re: Python 3.3 vs. MSDOS Basic Ian Kelly <ian.g.kelly@gmail.com> - 2013-02-18 15:15 -0700
  Re: Python 3.3 vs. MSDOS Basic Alexander Blinne <news@blinne.net> - 2013-02-19 01:11 +0100
  Re: Python 3.3 vs. MSDOS Basic Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-02-18 19:36 -0500
    Re: Python 3.3 vs. MSDOS Basic John Immarino <johimm@gmail.com> - 2013-02-18 17:47 -0800
    Re: Python 3.3 vs. MSDOS Basic John Immarino <johimm@gmail.com> - 2013-02-18 17:47 -0800
  Re: Python 3.3 vs. MSDOS Basic Terry Reedy <tjreedy@udel.edu> - 2013-02-18 19:50 -0500
    Re: Python 3.3 vs. MSDOS Basic Piet van Oostrum <piet@vanoostrum.org> - 2013-02-19 12:42 +0100
      Re: Python 3.3 vs. MSDOS Basic Alexander Blinne <news@blinne.net> - 2013-02-20 01:23 +0100
        Re: Python 3.3 vs. MSDOS Basic Ian Kelly <ian.g.kelly@gmail.com> - 2013-02-19 18:04 -0700
  Re: Python 3.3 vs. MSDOS Basic Terry Reedy <tjreedy@udel.edu> - 2013-02-19 00:28 -0500
  Re: Python 3.3 vs. MSDOS Basic Anssi Saari <as@sci.fi> - 2013-02-19 12:52 +0200
  Re: Python 3.3 vs. MSDOS Basic Serhiy Storchaka <storchaka@gmail.com> - 2013-02-19 13:13 +0200
  Re: Python 3.3 vs. MSDOS Basic Olive <diolu.remove_this_part@bigfoot.com> - 2013-02-19 15:02 +0100

csiph-web