[Spoiler] QotW 23

I haven't got the time to go through all the submissions yet, but I believe
mine is a new one. Not in the sense that it's better, but in the sense that
it's worst :-) Really, really worst, I would bet :-)

I haven't made decent tests with it, but I take it as it will probably be one
of the worse solutions for this quiz.

Why am I posting it then? Because it took me less than a minute to code, and
because it's good enough for the smaller cases :-) I just hope I got the output
right (I read something about the output for 0... oops)

#!/usr/bin/perl -wl
use strict;

( my $n = shift ) > 0 || die;

print for uniqs( parens($n) );

sub parens {
  $_[0]
    ? map { ( "$_()", "()$_", "($_)" ) } parens( $_[0] - 1 )
    : ('');
}

sub uniqs {
  my %v;
  grep { !$v{$_}++ } @_;
}

As you can see, recursion was not enough for me, so I had to do the same thing
more than once and then get the unique elements out of the list :-) (it would
be easy to take care of that, though).

Nice problem :-)

Solution goes attached, too...
With a comment or two...

:-)

-- 
José Alves de Castro <[email protected]>
  http://natura.di.uminho.pt/~jac

#!/usr/bin/perl -wl
use strict;
=head1

A little bit of recursion and here it is.

The program dies if no argument or a negative one is supplied.

This file has precisely 400 bytes :-)

=cut

( my $n = shift ) > 0 || die;

print for uniqs( parens($n) );

sub parens {
  $_[0]
    ? map { ( "$_()", "()$_", "($_)" ) } parens( $_[0] - 1 )
    : ('');
}

sub uniqs {
  my %v;
  grep { !$v{$_}++ } @_;
}