Re: [Bug-apl] Best way to solve my daughter's maths problem

[Elias Mårtenson]

But that's what my solution did. The problem is that that solution doesn't evaluate things like (4+4)×(4+4)-4

Regards,

Elias

On 25 January 2017 at 09:49, <address@hidden> wrote:

op ← '+-x÷'

i meant a brute force     creating a HUGE matrix       '(((4 op[⍳4] 4) op[⍳4] 4) op[⍳4] 4) op[⍳4] 4'





On Wed, 25 Jan 2017 08:49:37 +0800

Elias Mårtenson <address@hidden> wrote:

> Thanks, but the code I included already gives me that solution, so that was
> never the problem.
>
> The issue here is more one of trying to come up with a good APL solution. I
> really don't like mine, it's too verbose.
>
> Regards,
> Elias
>
> On 25 Jan 2017 8:46 AM, <address@hidden> wrote:
>
> > since no one has responded yet this is my best guess without pure random
> > code testing from array of chars following your rules
> >
> > the answer is :  ⍎'(((4+4)x4)-4)÷4'     ;)
> > i think the problem is from an episode of cartalk ??
> >
> >
> >
> > On Tue, 24 Jan 2017 23:47:10 +0800
> > Elias Mårtenson <address@hidden> wrote:
> >
> > > My daughter had this maths problem, and quote it from memory:
> > >
> > > Given five 4's, separated by the mathematical functions +, -, × and ÷
> > form
> > > the number 7. The problem also allowed her to use parentheses.
> > >
> > > I decided to write an APL _expression_ to solve this, and this is what I
> > came
> > > up with:
> > >
> > >
> > > *    d ← {⍵÷⍺}*
> > > *    (↑¨ 7 = ⍎¨ v) / v ← {"4 " , ↑,/ {{⍵," 4 "}¨⍵} ⍵}¨ ,↑∘.,/4 ⍴ ⊂'+-×d'*
> > >
> > > Now, this program finds two solutions, which is good enough for me.
> > > However, my program doesn't find solutions that require parentheses.
> > >
> > > Problem 1: Can anyone simplify my program?
> > > Problem 2: Can anyone come up with a solution that also checks for
> > > parentheses?
> > >
> > > Regards,
> > > Elias
> >
> >