整数转罗马数字

class Solution:
    def intToRoman(self, num: int) -> str:
        nums = [1000,900,500,400,100,90,50,40,10,9,5,4,1]
        romans = ['M','CM','D','CD','C','XC','L','XL','X','IX','V','IV','I']

        index = 0
        res = ''
        while index < 13:
            while num >= nums[index]:
                res += romans[index]
                num -= nums[index]

            index += 1

        return res