Roman_to_Integer.cpp

class Solution {
public:
    int romanToInt(string s) {
        unordered_map<char, int> hm;
        hm['I'] = 1;
        hm['V'] = 5;
        hm['X'] = 10;
        hm['L'] = 50;
        hm['C'] = 100;
        hm['D'] = 500;
        hm['M'] = 1000;
        
        int sum = 0;
        for(int i = 0; i < s.length()-1; i++){
            if(hm[s[i]] >= hm[s[i+1]]) sum += hm[s[i]];
            else sum += hm[s[i]]*-1;
        }
        
        sum += hm[s[s.length()-1]];
        
        return sum;
    }
};