Fun with Permutations (including new change for Facets)

ruby-talk
1

For some weird reason I was expecting reverse_each to be slower than
each, so I decided that reversing once and eaching multiple times would
be faster than multiple reverse_eaching - Benchmarking killed that myth
though. The saving however, is in the order of nanoseconds, as the
reverse only happens once.

Reversing an array with 10 elements took about a millionth of second on
my machine. Considering you're going to be iterating over 3.6 million
permutations, which takes somewhere in the order of 3 minutes, I decided
that extra optimisation wasn't necessary =)

I would have preferred if ((size-1)..0).each actually iterated, but
them's the breaks.

···

-----Original Message-----
From: Sean O'Halpin [mailto:sean.ohalpin@gmail.com]
Sent: Monday, 7 November 2005 11:36 AM
To: ruby-talk ML
Subject: Re: Fun with Permutations (including new change for Facets)

On 11/7/05, Daniel Sheppard <daniels@pronto.com.au> wrote:
> s = (0...size).to_a.reverse
> ...
> break if s.each { |i|

Did you know there is a reverse_each? Might shave off a
millisecond or two :wink:

Regards,

Sean

#####################################################################################
This email has been scanned by MailMarshal, an email content filter.
#####################################################################################

2

The saving however, is in the order of nanoseconds

Every little helps! :wink:

I would have preferred if ((size-1)..0).each actually iterated, but
them's the breaks.

How about (size-1).downto(0) {|i| ... } ?

Regards,

Sean

···

On 11/7/05, Daniel Sheppard <daniels@pronto.com.au> wrote: