Roman_to_Integer.md

13. Roman to Integer

Given a roman numeral, convert it to an integer.

Input is guaranteed to be within the range from 1 to 3999.

Method:

class Solution(object):
    def romanToInt(self, s):
        """
        :type s: str
        :rtype: int
        """
        res=0
        if "IV" in s or "IX" in s:
            res-=2
        if "XL" in s or "XC" in s:
            res-=20
        if "CD" in s or "CM" in s:
            res-=200
        d={'I':1, 'V':5, 'X':10, 'L':50, 'C':100, 'D':500, 'M':1000}
        for i in s:
            res+=d[i]
        return res

Solution:

class Solution(object):
    def romanToInt(self, s):
        """
        :type s: str
        :rtype: int
        """
        res=0
        d={'I':1, 'V':5, 'X':10, 'L':50, 'C':100, 'D':500, 'M':1000}
        for i in range(len(s)-1):
            if d[s[i]]>=d[s[i+1]]:
                res+=d[s[i]]
            else:
                res-=d[s[i]]
        return res+d[s[-1]]