LeetCode #13 罗马数字转整数

class Solution {
public:
    int romanToInt(string s) {
        map<string,int> roma={{"M",1000},{"D",500},{"C",100},{"L",50},{"X",10},{"V",5},{"I",1},{"#",-1}};
        int i=0;
        int ans=0;
        s.push_back('#');
        string str,str1;
        while(s[i]!='#'){
            str=s.substr(i,1);
            str1=s.substr(i+1,1);
            if(roma[str]<roma[str1]){
                ans-=roma[str];
            }
            else{
                ans+=roma[str];
            }
            i++;
        }
        return ans;
    }
};