ch13_class.rb

#Chapter 13.1

class Array
  def shuffle
    arr = self
    # Now we can just copy the old shuffle method
    shuf = []

    while arr.length > 0
      #Randomly pick one element
      rand_index = rand(arr.length)

      curr_index = 0
      new_arr = []
      arr.each do |item|
        if curr_index == rand_index
          shuf.push item
        else
          new_arr.push item
        end

        curr_index = curr_index + 1
      end

      arr = new_arr
    end
    shuf
  end
end
class Integer
  def factorial
    if self <= 1
      1
    else
      self * (self-1).factorial
    end
  end
  def to_roman
    roman = ''

    roman = roman + 'M' * (self  /1000)
    roman = roman + 'D' * (self % 1000 / 500)
    roman = roman + 'C' * (self % 500 / 100)
    roman = roman + 'L' * (self % 100 / 50)
    roman = roman + 'X' * (self % 50 / 10)
    roman = roman + 'V' * (self % 10 / 5)
    roman = roman + 'I' * (self % 5 / 1)

    roman
  end
end

puts [1,2,3,4,5].shuffle
puts 7.factorial
puts 73.to_roman