From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-11-03T19:44:49+09:00
Subject: Re: Regular Expression

On Wed, Nov 3, 2010 at 11:10 AM, Robert Klemme
<shortcutter@googlemail.com> wrote:
> Interesting approach.  I would simply have done
>
> def check(input)
>  raise ArgumentError, "Illegal chars in sequence: %p" % input unless
> /\A[A-D]{0,4}\z/ =~ input
>  cnt = Hash.new 0
>  input.scan /./ do |m|
>    raise ArgumentError, "Illegal sequence %p" % input if (cnt[m] += 1) > 1
>    # alt: return false
>  end
>  # alt: true
> end

There are different requirements for each letter. Adapting your solution:


def check(input)
  limits = {'A' => 1, 'B' => 1, 'C' => 1, 'D' => 2}
  raise ArgumentError, "Illegal chars in sequence: %p" % input unless
/\A[A-D]{0,4}\z/ =~ input
  cnt = Hash.new 0
  input.scan /./ do |m|
    cnt[m] += 1
  end

  cnt.each do |letter, amount|
    raise ArgumentError, "Illegal chars in sequence: %p" % input if
amount > limits[letter]
  end
end

Jesus.