Perl Christmas Quiz

[Paul Makepeace]

SPOILERS contd


On Fri, Dec 12, 2008 at 11:37 AM, Joel Bernstein <joel at fysh.org> wrote:
> 2008/12/12 Chris Jack <chris_jack at msn.com>:

>> 3) Write a Perl function that takes two references to arrays and returns the intersect of them. If an entry appears n times in array 1 and m times in array 2, the output should list that entry min(n,m) times. Bonus mark for one line solutions.
>
> use Set::Scalar;
> sub intersect (\@\@) {
>  my ($a1, $a2) = map { Set::Scalar->new(@$_) } @_;
>  my $intersection = $a1 * $a2;
>  return $intersection->elements;
> }

This isn't a set question though. Sets have unique membership,

stix:~$ perl -MSet::Scalar -le '$s = Set::Scalar->new(1,1); print $s->elements'
1

Something like,

sub intersect {
  my @s1 = sort @{$_[0]};
  my @s2 = sort @{$_[1]};
  my @s3;
  while (my $e = $s1[0]) {
    if ($e == $s2[0]) {
      push @s3, $e;
      shift @s2;
      shift @s1;
    } elsif ($e > $s2[0]) {
      shift @s2;
    } else {
      shift @s1;
    }
  }
  @s3;
}

There's probably some clever answer using List::MoreUtils.

P

>
> Surely you didn't want a wheel-reinvention answer? ;-)
>
>> 4) How many different variable types are there in Perl? Be as sensibly voluminous in your answer as you are able.
>
> SCALAR ARRAY HASH CODE
> FileHandle DirHandle Regexp
>
> But clearly we distinguish between numeric and string scalar values,
> so I'm wondering how exhaustive that list is...
>
>
>> 5) What animal is on the front of the Perl Cookbook (bonus mark for knowing both the first and second edition)?
>
> A horned sheep of some kind. Don't think I've ever seen the first ed though...
>
>> 7) What does the L in Randal L Schwartz stand for?
>
> Loser.
>
>> 8) Name a Perl module Leon (Brocard) has written (bonus mark if you've used it).
>
> Devel::ebug
>
>> 9) When will Perl 6 be released?
>
> Never.
>
> Bored now.
>
> /joel
>