integer to-roman

Problem

Seven different symbols represent Roman numerals with the following values:

Symbol	Value
I	1
V	5
X	10
L	50
C	100
D	500
M	1000

Roman numerals are formed by appending the conversions of decimal place values from highest to lowest. Converting a
decimal place value into a Roman numeral has the following rules:

• If the value does not start with 4 or 9, select the symbol of the maximal value that can be subtracted from the input,
  append that symbol to the result, subtract its value, and convert the remainder to a Roman numeral.
• If the value starts with 4 or 9 use the subtractive form representing one symbol subtracted from the following
  symbol, for example, 4 is 1 (I) less than 5 (V): IVand 9 is 1 (I) less than 10 (X): IX. Only the following
  subtractive forms are used: 4 (IV), 9 (IX), 40 (XL), 90 (XC), 400 (CD) and 900 (CM).
• Only powers of 10 (I, X, C, M) can be appended consecutively at most 3 times to represent multiples of 10. You
  cannot append 5(V), 50 (L), or 500 (D) multiple times. If you need to append a symbol 4 times use the subtractive form.

Given an integer, convert it to a Roman numeral.

Example 1:

Input: num = 3749

Output: “MMMDCCXLIX”

Explanation:

3000 = MMM as 1000 (M) + 1000 (M) + 1000 (M)
700 = DCC as 500 (D) + 100 (C) + 100 (C)
40 = XL as 10 (X) less of 50 (L)
9 = IX as 1 (I) less of 10 (X)
Note: 49 is not 1 (I) less of 50 (L) because the conversion is based on decimal places

Example 2:

Input: num = 58

Output: “LVIII”

Explanation:

50 = L
8 = VIII

Example 3:

Input: num = 1994

Output: “MCMXCIV”

Explanation:

1000 = M
900 = CM
90 = XC
4 = IV

Constraints:

• 1 <= num <= 3999

Approach

I basically just wanted to have a map of each roman symbol and their corresponding value. Then I could simply loop through the values as long as

Code

class Solution:
    def intToRoman(self, num: int) -> str:
        symbols = {
        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'}
 
        roman = ''
        for value in sorted(symbols.keys(), reverse=True):
            while num >= value:
                roman += symbols[value]
                num -= value
        return roman