【Roman To Integer】cpp

class Solution {
public:
    int romanToInt(string s) {
        const int size = 7;
        std::map<char, int> symbol_value;
        char symbol_ori[size] = {‘M‘,‘D‘,‘C‘,‘L‘,‘X‘,‘V‘,‘I‘};
        int value_ori[size] = {1000,500,100,50,10,5,1};
        for ( size_t i = 0; i < size; ++i ) 
            symbol_value[symbol_ori[i]]=value_ori[i];

        int result = symbol_value[s[0]];
        for ( size_t i = 1; i < s.size(); ++i )
        {
            if ( symbol_value[s[i]] > symbol_value[s[i-1]] )
            {
                result += symbol_value[s[i]] - 2*symbol_value[s[i-1]];
            }
            else
            {
                result += symbol_value[s[i]];
            }
        }
        return result;
    }
};