24 game/Solve: Difference between revisions

=={{header|J}}==

<lang J>perm=: (A.&i.~ !) 4

ops=: ' ',.'+-*%' {~ >,{i.each 4 4 4

cmask=: 1 + 0j1 * i.@{:@$@[ e. ]

left=: [ #!.'('~"1 cmask

right=: [ #!.')'~"1 cmask

paren=: 2 :'[: left&m right&n'

parens=: ], 0 paren 3, 0 paren 5, 2 paren 5, [: 0 paren 7 (0 paren 3)

all=: [: parens [:,/ ops ,@,."1/ perm { [:;":each

answer=: ({.@#~ 24 = ".)@all</lang>

This implementation tests all 7680 candidate sentences.

Example use:

answer 2 3 5 7

2+7+3*5

The answer will be either a suitable J sentence or blank if none can be found.