roman_to_integer.cpp

#include <string.h>
#include <iostream>
using namespace std;

class Solution
{
public:
    /**
     * @brief Extracts the value of a roman number from its char form
     * @version 0.1
     * @author Bastien LANGUE (bastien.langue@reseau.eseo.fr)
     * @date 06.24.2022
     * @copyright Copyright (c) 2022
     *
     * @param         c              (char) the roman number in char form
     * @return (int) The corresponding value
     */
    int extractValue(char c)
    {
        int ret = 0;
        switch (c)
        {
        case 'I':
            ret = 1;
            break;
        case 'V':
            ret = 5;
            break;
        case 'X':
            ret = 10;
            break;
        case 'L':
            ret = 50;
            break;
        case 'C':
            ret = 100;
            break;
        case 'D':
            ret = 500;
            break;
        case 'M':
            ret = 1000;
            break;
        default:
            break;
        }
        return ret;
    }

    /**
     * @brief Runs through the roman number char by char and sums up the result
     * @version 0.1
     * @author Bastien LANGUE (bastien.langue@reseau.eseo.fr)
     * @date 06.24.2022
     * @copyright Copyright (c) 2022
     *
     * @param         s              (string) The roman number in string form
     * @return (int) the resulting value of the roman number
     */
    int romanToInt(string s)
    {
        int res = 0;
        for (size_t i = 0; i < s.length(); i++)
        {
            if (i != s.length() - 1 && extractValue(s.at(i)) < extractValue(s.at(i + 1)))
                res -= extractValue(s.at(i));
            else
                res += extractValue(s.at(i));
        }
        return res;
    }
};

RomanToInteger.md

RomanToInt optimal algorithm

Reusable Roman Number to Integer function See reference exercise