use List::Util qw{ any };

my @RE = (qr/[[:lower:]]/, qr/[[:upper:]]/, qr/[0-9]/, qr/[^[:alnum:]]/);
sub check {
    my ($password) = @_;
    my $length = length $password;
    return if $length < 8;
    return if $length < 12 && any { $password !~ $RE[$_] } 0 .. 3;
    return if $length < 16 && any { $password !~ $RE[$_] } 0 .. 2;
    return if $length < 20 && any { $password !~ $RE[$_] } 0 .. 1;
    return 1
}