From: Mk 27 <halfcountplus@...>
Date: 2009-05-18T08:43:19+09:00
Subject: Re: permute each element of a ragged array?

Phlip wrote:
> Rubies:
> 
> Here's a programming chestnut. I suppose I could brute-force my way 
> through
> this, 

I'm not the kind of person who would already know the answer to this, 
but I kind of think it is de facto the same as what "brute force" is -- 
an attempt to cover every possibility.  Almost.

One optimization that springs to mind immediately would be that if you 
progress through the array one element at a time and match all possible 
permutations, eg given 1,2,3 with 1 @ 0:

1
1 1
1 1 1
1   1
1 2
 ...etc

when doing permutations subsequently with 1 @ 1 you can neglect 
everything with 1 @ 0.  So by the time you reach 1 @ 2, you can limit to

    1
  2 1
2   1
2 2 1
2 3 1
   ...etc

One step away from a straight iterative "brute force".



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