How to subtract an array from an array / Array minus Array - PERL

Question

I have arrays like below and I can't find good solutions to make it works:

my @a = qw( A A B C C D D );

my @b = qw( A B C C D );

and as a result I would like to get: @a - @b = (A D)

Thanks for help!

Answer 1

my %b;
++$b{$_} for @b;
grep { --$b{$_} < 0 } @a

Answer 2

You can find some code an explanation here: http://www.perlmonks.org/?node_id=2461