roman numerals

お題

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を書きなさい¹．

ローマ数字で使われる文字

arabic numerals	roman numerals
1	I
5	V
10	X
50	L
100	C
500	D
1000	M

例

arabic numerals	roman numerals
1	I
2	II
4	IV
5	V
6	VI
9	IX
10	X
11	XI
14	XIV
15	XV
19	XIX
38	XXXVIII
42	XLII
49	XLIX
51	LI
97	XCVII
99	XCIX
439	CDXXXIX
483	CDLXXXIII
499	CDXCIX
732	DCCXXXII
961	CMLXI
999	CMXCIX
1999

最終

# coding: utf-8
def romanize(number)
  a=[1000,900,500,400,100,90,50,40,10,9,5,4,1]
  r=["M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"]
  roman=[]

  number=number.to_i

  if (number > 0 and number < 4000) then
    for i in 0..12 do
      while number>=a[i] do
	roman.push(r[i])
	number-=a[i]
      end
    end
  else
    puts "変換できません"
  end

  puts roman.join(' ')
end



puts "アラビア数字を入力してください"
n=gets
romanize(n)

発展

整数はInteger classです．hello classを参照して，Integer classを拡張して，

999.to_roman #=> CMXCIX

と返すようにしなさい．

# coding: utf-8
def romanize(number)
  a=[1000,900,500,400,100,90,50,40,10,9,5,4,1]
  r=["M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"]
  roman=[]

  number=number.to_i

  if (number > 0 and number < 4000) then
    for i in 0..12 do
      while number>=a[i] do
	roman.push(r[i])
	number-=a[i]
      end
    end
  else
    puts "変換できません"
  end

  puts roman.join(' ')
end



puts "アラビア数字を入力してください"
n=gets
romanize(n)

参照文献

---

• source ~/grad_members_20f/members/NobuakiMori/ex_roman_numerals.org

1. "初めてのプログラミング", Chris Pine (著), 西山 伸 (翻訳),オライリー・ジャパン (2006/7/24). ↩