recursive algorithm for balls in numbered boxes

Peter Otten __peter__ at
Sun Sep 11 16:13:02 EDT 2011

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

without realizing it was not

> 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.

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