13. Roman to Integer

Hint

class Solution {
public:
    int romanToInt(string s)
    {
        // Create a map to store Roman numeral characters and their integer values

        // Initialize the result variable to store the final integer value
        // Loop through each character in the string
        for ()
        {
            // Check if the current character value is less than the next character value
                // If true, subtract the current character's value from the result
                // Otherwise, add the current character's value to the result
        }
        // Return the final integer value
    }
};

class Solution {
public:
    int romanToInt(string s)
    {
        unordered_map<char, int> m = {
            {'I', 1},
            {'V', 5},
            {'X', 10},
            {'L', 50},
            {'C', 100},
            {'D', 500},
            {'M', 1000},
        };

        int res = 0;
        for (int i = 0; i < s.size(); ++i)
        {
            if (i < s.size() - 1 && m[s[i]] < m[s[i + 1]])
            {
                res -= m[s[i]];
            }
            else
            {
                res += m[s[i]];
            }
        }
        return res;
    }
};

• T: $O(N)$
• S: $O(1)$