Day_056.cpp

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