Roman to Integer.

#include <iostream>
#include <unordered_map>
#include <string>

using namespace std;

class Solution {
public:
    int romanToInt(string s) {
        unordered_map<char, int> romanVal = {
            {'I', 1},
            {'V', 5},
            {'X', 10},
            {'L', 50},
            {'C', 100},
            {'D', 500},
            {'M', 1000}
        };
        int sum = romanVal[s.back()];
        for (int i = s.size() - 2; i >= 0; --i)
        {
            if (romanVal[s[i]] < romanVal[s[i + 1]])
            {
                sum -= romanVal[s[i]];
            }
            else
            {
                sum += romanVal[s[i]];
            }
        }
        return sum;
    }
};

int main(void)
{
    Solution s;
    string romanNum;
    cout << "Roman Number: ";
    getline(cin, romanNum);
    cout << "Integer Number: " << s.romanToInt(romanNum) << "\n\n";
    return 0;
}