my @a = ( 1, 2, 3 );
my @b = ( 2, 3, 1 );
my @c = ( 1, 2, 4 );

print "(@a) and (@b) are equal sets.\n" if identical( \@a, \@b );
print "(@a) and (@c) are equal sets.\n" if identical( \@a, \@c );
print "(@b) and (@c) are equal sets.\n" if identical( \@b, \@c );

sub identical {
    my( $left, $right ) = @_;
    return 0 if scalar @$left != scalar @$right;
    my %hash;
    @hash{ @$left, @$right } = ();
    return scalar keys %hash == scalar @$left;
}