Just for fun: Countdown numbers game solver

Arnaud Delobelle arnodel at googlemail.com
Mon Jan 21 12:27:45 CET 2008

On Jan 21, 9:12 am, Terry Jones <te... at jon.es> wrote:
> Hi Arnaud.

Hi Terry

> WRT to the missing solution, note that my code only allowed multiplication
> by 1 if it was the last thing done. That was because you can multiply by 1
> at any time, and I didn't want to see those trivially equivalent solutions
> (same goes for adding 0). Seeing as you're allowed to omit numbers, I've
> now gotten rid of those trivial operations altogether in my solution.

Sorry I gave an incorrect example to illustrate my question last night
(I blame this on baby-induced sleep deprivation ;), so I'll have
another go:

Say I have 2, 3, 4, 100 and I want to make 406.  AFAICS there is only
one way: (2*3)+(4*100), i.e. in postfix notation:

2 3 * 4 100 * +

It seemed to me that your function wouldn't generate that sort of
solution (as you always extend partialSolution by [num, op] making the
subsequence [mul, add] impossible).  Am I wrong?


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