"""
Solution for 13. Roman to Integer
https://leetcode.com/problems/roman-to-integer/
"""

class Solution:
    """
    Runtime: 64 ms, faster than 98.56% of Python3 online submissions for Roman to Integer.
    Memory Usage: 13.3 MB, less than 5.05% of Python3 online submissions for Roman to Integer.
    """
    def romanToInt(self, s):
        """
        Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

        Symbol       Value
        I             1
        V             5
        X             10
        L             50
        C             100
        D             500
        M             1000
        For example, two is written as II in Roman numeral, just two one's added together. Twelve
        is written as, XII, which is simply X + II. The number twenty seven is written as XXVII,
        which is XX + V + II.

        Roman numerals are usually written largest to smallest from left to right. However, the
        numeral for four is not IIII. Instead, the number four is written as IV. Because the one
        is before the five we subtract it making four. The same principle applies to the number
        nine, which is written as IX. There are six instances where subtraction is used:

        I can be placed before V (5) and X (10) to make 4 and 9.
        X can be placed before L (50) and C (100) to make 40 and 90.
        C can be placed before D (500) and M (1000) to make 400 and 900.
        Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range
        from 1 to 3999.

        Example 1:

        Input: "III"
        Output: 3
        Example 2:

        Input: "IV"
        Output: 4
        Example 3:

        Input: "IX"
        Output: 9
        Example 4:

        Input: "LVIII"
        Output: 58
        Explanation: L = 50, V= 5, III = 3.
        Example 5:

        Input: "MCMXCIV"
        Output: 1994
        Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.
        Args:
            s: str to convert to integer from

        Returns:
            int: integer from roman string
        """
        hash_table = {
            'M': 1000,
            'D': 500,
            'C': 100,
            'L': 50,
            'X': 10,
            'V': 5,
            'I': 1,
        }

        maximum = 9999
        accumulated = 0

        for i in range(len(s)):
            if hash_table[s[i]] > maximum:
                accumulated = accumulated + hash_table[s[i]] - hash_table[s[i - 1]] * 2
            else:
                accumulated += hash_table[s[i]]

            maximum = hash_table[s[i]]

        return accumulated
