Roman to Integer and Integer to Roman

'''
Following is the list of Roman symbols which include subtractive cases also:

SYMBOL       VALUE
I             1
IV            4
V             5
IX            9
X             10
XL            40
L             50
XC            90
C             100
CD            400
D             500
CM            900
M             1000
Idea is to convert the units, tens, hundreds, and thousands places of the given number separately. If the digit is 0, then there's no corresponding Roman numeral symbol. The conversion of digit's 4's and 9's are little bit different from other digits because these digits follows subtractive notation.
'''
class Solution:
    def intToRoman(self, num: int) -> str:
        d = {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'}
        res=""
        for val,sym in d.items():#dictionary should store the order perfectly or else use simplelist
            count,num=divmod(num,val)
            if count:res+=(sym*count)
        return res

#Roman to Integer:
class Solution:
    def romanToInt(self, s: str) -> int:
        d={'L':1,'V':5,'X':10,'L':50,'C':100,'D':500,'M':1000,'I':1}
        n=len(s)
        sum=d[s[-1]]
        for i in range(n-2,-1,-1):
            if d[s[i]]<d[s[i+1]]:sum-=d[s[i]] #If order breaks substract
            else:sum+=d[s[i]]#else add
        return sum