This removes inner matched pairs repeatedly and analyzes what's left.
Suitable if the nesting level is not very high. Should be 3 lines.
pairs =. _2 ]\ '()[]{}'
remnant =: (#~ [: (+: _1&(|.!.0)) [: +./ pairs&(E."1))^:_ @ (#~
e.&(,pairs))
balanced =: ( *...@# + *...@#@(-.&({."1 pairs)) )@remnant
balanced '()[]'
0
balanced '()[]('
1
balanced '()[](]'
2
Henry Rich
Chris Burke wrote:
> How to check if a string has balanced [] {} ()?
>
> Any pair by itself is easy enough, but I want to check all three balance
> together, e.g.
>
> ...[(])...
>
> would fail. Assume there are no character strings.
>
> Ideally, I'd like a result of
>
> 0 = balanced
> 1 = balanced so far, but some closing delimiters to come
> 2 = unbalanced (and broken)
>
>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
