Class: Luhn

Inherits:
Object
  • Object
show all
Defined in:
lib/luhn.rb

Class Method Summary collapse

Class Method Details

.checksum(number) ⇒ Object 



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# File 'lib/luhn.rb', line 3

def self.checksum(number)
  products = luhn_doubled(number)
  sum = products.inject(0) { |t,p| t + sum_of(p) }
  checksum = 10 - (sum % 10)
  checksum == 10 ? 0 : checksum
end

.luhn_doubled(number) ⇒ Object 



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# File 'lib/luhn.rb', line 10

def self.luhn_doubled(number)
  numbers = split_digits(number).reverse
  numbers.map.with_index do |n,i|
    i.even? ? n*2 : n*1
  end.reverse
end

.split_digits(number) ⇒ Object 



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# File 'lib/luhn.rb', line 26

def self.split_digits(number)
  number.to_s.split(//).map(&:to_i)
end

.sum_of(number) ⇒ Object 



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# File 'lib/luhn.rb', line 17

def self.sum_of(number)
  split_digits(number).inject(:+)
end

.valid?(number) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/luhn.rb', line 21

def self.valid?(number)
  numbers = split_digits(number)
  numbers.pop == checksum(numbers.join)
end