Perl Christmas Quiz

[Robin Barker]

My haskell solution:

import List (delete) 
intersection :: Eq a => [a] -> [a] -> [a]
intersection [] _ = []
intersection (x:xs) ys = if elem x ys then x: (intersection xs (delete x ys))
							else intersection xs ys

My Perl solution:

sub intersection {
    my ($a, $b) = @_;
    my %c;
    $c{$_}++ for @$b;
    return [ grep {$c{$_} and $c{$_}--} @$a ];
}   

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