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From: Peter Otten <__peter__@web.de>
Subject: Re: recursive algorithm for balls in numbered boxes
Date: Sun, 11 Sep 2011 22:13:02 +0200
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:13149

Dr. Phillip M. Feldman wrote:

> When I run my code, I get the same 14 configurations that your code
> produces; 

I'm sorry, I ran the buggy code from

http://old.nabble.com/file/p32439307/balls_in_numbered_boxes.py

without realizing it was not 

http://old.nabble.com/file/p32440187/balls_in_numbered_boxes.py

> the only different that I can see in the output is that the
> configurations are produced in a different order.  Note that your code is
> not creating an iterator, so thus doesn't do what I want.  

The outer loop is in a generator expression and thus evaluates lazily.

> Also,
> generating the product set and then testing whether the total number of
> balls is correct will potentially consider a huge number of cases that
> must be rejected because the sum is wrong; this is too inefficient.

Indeed; I should have added a disclaimer to make that clear.