James Gray
5/5/2007 6:21:00 PM
Begin forwarded message:
> From: Kai Weingärtner <KaiWeing@gmx.net>
> Date: May 5, 2007 7:48:53 AM CDT
> To: submission@rubyquiz.com
> Subject: Please Forward: Ruby Quiz Submission (please update)
>
>
> Hello,
>
> I first sent you my solution as a tar attachement. This version is
> plain text and much easier to read ;-)
> Could you please replace my solution?
>
> Thank You!
>
> Kai Weingärtner
>
> The card check implementation:
>
> class CardCheck
> attr_reader :number
>
> @@types = {
> 'AMEX' => {:starts_with => [34, 37], :length => [15]},
> 'Discover' => {:starts_with => [6011], :length => [16]},
> 'MasterCard' => {:starts_with => (51..55), :length => [16]},
> 'Visa' => {:starts_with => [4], :length => [13, 16]}
> }
>
> def initialize(num)
> @number = num.to_s
> end
>
> def type
> @@types.each do |card_name, type_checks|
> starts_with = type_checks[:starts_with]
> lengths = type_checks[:length]
> fits_length = lengths.any? {|length| @number.length == length}
> fits_start = starts_with.any? {|start| @number.match('^' +
> start.to_s)}
> return card_name if (fits_length and fits_start)
> end
> return 'Unknown'
> end
>
> def calc_luhn
> elements = []
> @number.reverse.split(//).each_with_index do |digit, index|
> if (index.even?)
> elements << digit
> else
> elements << (digit.to_i * 2).to_s.split(//)
> end
> end
> return elements.flatten.sum
> end
>
> def is_valid?
> return (calc_luhn % 10) == 0
> end
>
> private :calc_luhn
> end
>
> class Integer
> def even?
> (to_i % 2) == 0
> end
> end
>
> module Enumerable
> def to_i
> collect {|x| x.to_i}
> end
>
> def sum
> to_i.inject {|sum, x| sum + x}
> end
>
> The command line interpreter
>
> require 'card_check'
>
> unless ARGV[0]
> print <<-USAGE
> Checks card vendor and validity
> Usage: provide the card number
> USAGE
> exit
> end
>
> card = CardCheck.new(ARGV[0])
> puts "Card type: #{card.type}\n"
> puts "Number valid? #{card.is_valid?}\n"
>
> some tests...
>
> require 'card_check'
> require 'test/unit'
> class TestCardCheck < Test::Unit::TestCase
> def test_validity
> assert_equal(true, CardCheck.new("4408041234567893").is_valid?)
> assert_equal(false, CardCheck.new("4417123456789112").is_valid?)
> end
>
> def test_type
> assert_equal('Visa', CardCheck.new("4408041234567893").type)
> assert_equal('AMEX', CardCheck.new("340804123456789").type)
> assert_equal('Discover', CardCheck.new("6011440804123456").type)
> assert_equal('MasterCard', CardCheck.new("5308041234567893").type)
> assert_equal('Visa', CardCheck.new("4408041234567").type)
> assert_equal('Unknown', CardCheck.new("9408041234567893").type)
> end
> end
>