One-pass version:
pairs =. _2 ]\ '()[]{}'
remnant =: (2&}.)^:(pairs e.~ 2&{.)@,/@(#~ e.&(,pairs))
balanced =: (+&(*...@#) -.&({."1 pairs))@remnant
Henry Rich
Henry Rich wrote:
> 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)
>>
>>
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>>
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