Groups > comp.lang.java.programmer > #4104

Re: Did the sort do anything?

From	Gene <gene.ressler@gmail.com>
Newsgroups	comp.lang.java.programmer
Subject	Re: Did the sort do anything?
Date	2011-05-14 21:49 -0700
Organization	http://groups.google.com
Message-ID	<a5cc61c3-8ac4-46e1-823c-9d3251f9f67a@glegroupsg2000goo.googlegroups.com> (permalink)

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On Tuesday, May 10, 2011 11:06:38 AM UTC-4, Roedy Green wrote:
> Often you sort things when they are already sorted. 
> 
> I am interested in simple algorithms to detect whether the sort
> actually did anything.
> 
> Some suggestions:
> 
> 1. do a pairwise compare of the times before the sort, and if all is
> in order, bypass the sort.

If you suspect that the list is close to sorted, you can do one bubble sort pass moving out-of-place elements to their correct locations.  At the same time you can track whether this pass produces a completely sorted list and call the library sort if that's not the case.

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Re: Did the sort do anything? Gene <gene.ressler@gmail.com> - 2011-05-14 21:49 -0700
  Re: Did the sort do anything? Lew <noone@lewscanon.com> - 2011-05-15 07:07 -0400
    Re: Did the sort do anything? Robert Klemme <shortcutter@googlemail.com> - 2011-05-15 14:07 +0200

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