Just for fun: Countdown numbers game solver

[david.hotham at blueyonder.co.uk]

On Jan 28, 10:11 pm, Arnaud Delobelle <arno... at googlemail.com> wrote:
> My strategy was to walk through each solution "only once" (for a
> certain definition of "only once :), thus I was hoping not to need a
> hashtable.

Yes, that seems like it should be preferable (and indeed necessary for
a more general problem with larger numbers of seeds).  But I wasn't
smart enough to figure out how to do it ;-)

> Did you pick these numbers at random?  Interestingly, the solution is
> unique:

Not at random -  this particular puzzle came out of the first post in
this thread.

>  Mine is faster on this example, but one example is not representative!

If you've found an efficient way to walk through the possible
solutions only once, then
-  I expect that yours will be faster
-  and well done!

I guess I should try to understand your code...

> --
> Arnaud