Roman to Integer

class Solution {
public:
    int romanToInt(string s) {
        int map[256];
        map[‘I‘]=1;map[‘V‘]=5;map[‘X‘]=10;map[‘L‘]=50;map[‘C‘]=100;map[‘D‘]=500;map[‘M‘]=1000;
        int i=-1,len=s.length(),ans=0;
        while(++i<len){
            if(i+1<len&&map[s[i]]<map[s[i+1]]){
                ans-=map[s[i]];
            }
            else
                ans+=map[s[i]];
        }
        return ans;
    }
};