in reply to Perl Golf-- testing array intersection

Both your and Errto’s solutions violate your spec: they will ignore duplicate elements in @x, but they report duplicate matches in @y.

The best I’ve come up with that works correctly is 49 characters (or 51 if you care about the context issue).

sub aristotle {
#        1         2         3         4
#234567890123456789012345678901234567890123456789
@_{@x}=(1)x@x;$_|=2for@_{@y};grep$_{$_}==3,keys%_
}

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Makeshifts last the longest.

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Re^2: Perl Golf-- testing array intersection
by Errto (Vicar) on Jan 30, 2006 at 22:17 UTC
    My interpretation of the spec allowed that behavior but ok, here's one at 45 chars that follows the duplicate rule: 
    sub match {
# 123456789012345678901234567890123456789012345
  ++$c{$_}for@x;++$d{$_}for@y;grep$d{$_},keys%c
}

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[d/l]
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