roman numerals

!Mac OS X-10.15.7 !ruby-2.7.1p83

課題

アラビア数字(arabic numerals)を受け取って，ローマ数字(roman numerals)を返すmethodを作成する．

コード

def to_roman(num)
  roman=['I','V','X','L','C','D','M']
  num_s=ARGV[0]
  num=num_s.to_i
  x=num/1000  #1000の位
  num=num%1000
  y=num/100   #100の位
  num=num%100
  z=num/10    #10の位
  num=num%10
  w=num       #1の位
  case x
  when 1,2,3 then
    result=roman[6]*x
  end

  case y
  when 1,2,3 then
    result+=roman[4]*y
  when 4 then
    result+=roman[4]+roman[5]
  when 5 then
    result+=roman[5]
  when 6,7,8 then
    result+=roman[5]+roman[4]*(y-5)
  when 9 then
    result+=roman[4]+roman[6]
  end

  case z
  when 1,2,3 then
    result+=roman[2]*z
  when 4 then
    result+=roman[2]+roman[3]
  when 5 then
    result+=roman[3]
  when 6,7,8 then
    result+=roman[3]+roman[2]*(z-5)
  when 9 then
    result+=roman[2]+roman[4]
  end

  case w
  when 1,2,3 then
    result+=roman[0]*x
  when 4 then
    result+=roman[0]+roman[1]
  when 5 then
    result+=roman[1]
  when 6,7,8 then
    result+=roman[1]+roman[0]*(x-5)
  when 9 then
    result+=roman[0]+roman[2]
  end
  return result
end

puts "#{to_roman(ARGV[0])}"

結果

>ruby roman_numeral.rb 1960

MCMLX

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• source ~/grad_members_20f/members/Kenny0704/roman.org