Re: radomize a number list

Tech-Archive recommends: Fix windows errors by optimizing your registry

From: Jon Skeet [C# MVP] (skeet_at_pobox.com)
Date: 06/03/04 

Date: Thu, 3 Jun 2004 06:20:22 +0100

William Stacey [MVP] <staceywREMOVE@mvps.org> wrote:
> Here is a Permuted Order class to find the next permutation of any ArrayList
> using Lexicographic order based on HashCodes.
> I would prefer to use Object Reference int as the order key as would not
> have to call GetHashCode() on each object in arraylist, but can't figure out
> a way to get object ref int in a safe context. Maybe not good either as GC
> can move refs - right?

Indeed. I'm concerned that your algorithm is assuming that two objects
with the same hashcode are different though... if you give your
algorithm a list with two objects which are unequal but have the same
hashcode, I believe it will treat them as being the same, incorrectly.

One way of getting round that would just be to assign each object a
sequential number, making sure that you assign equal objects the same
number. You could put that number in a hash table, for instance, so you
could look it up in order to do the comparison.
  

-- 
Jon Skeet - <skeet@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

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