I would suggest to use a bit map to figure out the diff between two arrays:

@a = (10, 2, 3, 5, 89);
@b = (2, 5);
my $c = [];

foreach (@a) {
    $c[$_] = $_;
};

foreach (@b) {
    $c[$_] = undef;
}

foreach (0 .. $#{@c}) {
    print "$c[$_]\n" if (defined($c[$_]));
}
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