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 <[email protected]> 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
