Re: [SPOILER] Solution for QOTW 23

Mark Jason Dominus wrote:
> I'm really pleased with this.  And I'm glad about the 60-hour
> moratorium, because my first couple of solutions weren't nearly as
> excellent.
> 
> #!/usr/bin/perl -l
> 
> print $_ = "()" x shift;
> print while s{^  ( \(+ )  ( \)+ ) \(  }
>              {"()" x (length($2) - 1)
>               . "("  x (length($1) - length($2) + 2) 
>               . ")" 
>              }xe;
> 
> 
> 
> __END__
> That's all.
> 
> :) :) :D
> 
Despite extensive fiddling, I don't have any intuitive notion of why 
this should produce all strings.  I can see how a valid start string, 
when run through the s/// will produce another valid string, but I can't 
wrap my head around precisely what's happening or, even more murky, how 
you thought this one up.  Can you shed some light for the not-quite-perl 
/algorithmic-hackers?

jweed

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