Checkio: Roman numerals

题目：

Roman numerals come from the ancient Roman numbering system. They are based on specific letters of the alphabet which are combined to signify the sum (or, in some cases, the difference) of their values. The first
ten Roman numerals are:

I, II, III, IV, V, VI, VII, VIII, IX, and X.

The Roman numeral system is decimal based but not directly positional and does not include a zero. Roman numerals are based on combinations of these seven symbols:

Symbol Value
I 1 (unus)
V 5 (quinque)
X 10 (decem)
L 50 (quinquaginta)
C 100 (centum)
D 500 (quingenti)
M 1,000 (mille)

More additional information about roman numerals can be found on the
Wikipedia article.

For this task, you should return a roman numeral using the specified integer value ranging from 1 to 3999.

Input: A number as an integer.

Output: The Roman numeral as a string.

Example:

checkio(6)=='VI'
checkio(76)=='LXXVI'
checkio(13)=='XIII'
checkio(44)=='XLIV'
checkio(3999)=='MMMCMXCIX'

How it is used: This is an educational task that allows you to explore
different numbering systems. Since roman numerals are often used in the typography, it can alternatively be used for text generation. The year of construction on building faces and cornerstones is most often written by Roman numerals. These numerals have many
other uses in the modern world and you read about it here... Or maybe you will have a customer from
Ancient Rome ;-)

Precondition: 0 < number < 4000
我的代码如下，尽管比较简单，我觉得这个代码算是比较清晰的了。

def checkio(data):

s = ''
ones = ['X','I', 'II', 'III', 'IV', 'V', 'VI', 'VII', 'VIII', 'IX']
tens = ['C', 'X', 'XX', 'XXX', 'XL', 'L', 'LX', 'LXX', 'LXXX', 'XC']
mils = ['M', 'C', 'CC', 'CCC', 'CD', 'D', 'DC', 'DCC', 'DCCC', 'CM']

if data / 1000 != 0:
s = s + 'M'*(data/1000)
data = data % 1000
if data / 100 != 0:
s = s + mils[data/100]
data = data % 100
if data / 10 != 0:
s = s + tens[data/10]
data = data % 10
if data / 1 != 0:
s = s + ones[data/1]
return s

if __name__ == '__main__':
#These "asserts" using only for self-checking and not necessary for auto-testing
assert checkio(6) == 'VI', '6'
assert checkio(76) == 'LXXVI', '76'
assert checkio(499) == 'CDXCIX', '499'
assert checkio(3888) == 'MMMDCCCLXXXVIII', '3888'

下面是checkio上面clear里面最火的答案：

elements = { 1000 : 'M', 900 : 'CM', 500 : 'D', 400 : 'CD',
100 : 'C', 90 : 'XC', 50 : 'L', 40: 'XL',
10 : 'X', 9 : 'IX', 5 : 'V', 4: 'IV', 1 : 'I' }

def checkio(data):
roman = ''

for n in sorted(elements.keys(), reverse=True):
while data >= n:
roman += elements

data -= n

return roman

看了吧，总是有人思路更清晰些。Come and On!