From: Jan_K <non@...>
Date: 2006-04-04T03:23:46+09:00
Subject: Re: Learn to Program, by Chris Pine

Chapter 9, exercise 2 (page 76)

Old-school Roman numerals. In the early days of Roman numerals,
the Romans didn�t bother with any of this new-fangled subtraction
IX nonsense. No sir, it was straight addition, biggest to littlest - 
so 9 was written VIIII, and so on. Write a method that, when
passed an integer between 1 and 3000 (or so), returns a string
containing the proper old-school Roman numeral. In other words,
old_roman_numeral 4 should return 'IIII'. Make sure to test
your method on a bunch of different numbers. Hint: Use the integer
division and modulus methods on page 36.
For reference, these are the values of the letters used:
I = 1 V = 5 X = 10 L = 50
C = 100 D = 500 M = 1000


Solution:
----------------------------------------------------------------
def old_roman_number input
  
  while input < 1 || input > 3999
    puts 'Please enter a number between 1 and 3999'
    input = gets.chomp.to_i
  end
  
  m_mod = input%1000  
  d_mod = input%500
  c_mod = input%100
  l_mod = input%50
  x_mod = input%10
  v_mod = input%5
  
  m_div = input/1000
  d_div = m_mod/500
  c_div = d_mod/100
  l_div = c_mod/50
  x_div = l_mod/10
  v_div = x_mod/5
  i_div = v_mod/1

  m = 'M' * m_div
  d = 'D' * d_div
  c = 'C' * c_div
  l = 'L' * l_div
  x = 'X' * x_div
  v = 'V' * v_div
  i = 'I' * i_div

  puts m + d + c + l + x + v + i  

end

number = gets.chomp.to_i
old_roman_number(number)
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