check for hash key and set it if it doesn't exist

#!/usr/bin/perl

use strict;
use warnings;

my @results = (0, 1, 0, 0, 1);

my $i = 0;
my %h;
for my $key (qw/a a b c b/) {
	my $bool = exists $h{$key} ? 1 : ($h{$key} = 0);
	print $bool == $results[$i++] ? "good" : "bad", "\n";
}