Roman to Integer

Roman numerals are represented by seven symbols: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000).

Typically, numerals are written from largest to smallest, and their values are summed. For instance, XII is 10 + 1 + 1 = 12, and LVIII is 50 + 5 + 1 + 1 + 1 = 58.

However, there are specific cases where a smaller numeral precedes a larger one, indicating subtraction. These are:

• I before V (4) or X (9)
• X before L (40) or C (90)
• C before D (400) or M (900)

Given a Roman numeral string, convert it to its corresponding integer value.

Example 1:

Input: s = "III" Output: 3

Example 2:

Input: s = "LVIII" Output: 58

Example 3:

Input: s = "MCMXCIV" Output: 1994

Constraints:

• The input string s will have a length between 1 and 15, inclusive.
• s will only contain the characters 'I', 'V', 'X', 'L', 'C', 'D', 'M'.
• The input s is guaranteed to represent a valid Roman numeral within the range [1, 3999].

Similar LeetCode problem: Roman to Integer