leetcode第13题

题目：将罗马数字转化为10进制数
C++：

int romanToInt(string s) {
        map<char, int> symbol = {
            {'I', 1}, {'V', 5}, {'X', 10}, {'L', 50}, {'C', 100}, {'D', 500}, {'M', 1000}
        };
        int value = 0;
        for(int i = s.length() - 1 ; i >= 0 ; i--)
        {
            if(i - 1 >= 0 && symbol[s.at(i)] > symbol[s.at(i - 1)])
            {
                value += symbol[s.at(i)] - symbol[s.at(i - 1)];
                i --;      
                continue;
            }
            value += symbol[s.at(i)];
        }
        return value;
    }

python：

def romanToInt(self, s):
        symbol = {"I":1, "V":5, "X":10, "L":50, "C":100, "D":500, "M":1000}
        value = 0
        i = len(s)
        while(i >= 0):
            i = i - 1
            if i < 0:
                break;
            if (i - 1) >= 0 and symbol[s[i]] > symbol[s[i - 1]]:
                value += symbol[s[i]] - symbol[s[i - 1]]
                i = i - 1
                continue

            value += symbol[s[i]]
        return value