Problem Statement

Given the Roman numeral string s, convert it into its equivalent integer and return it.

Roman numerals use combinations of seven symbols: I, V, X, L, C, D, and M, representing values 1, 5, 10, 50, 100, 500, and 1000 respectively.

For example, I is equivalent to 1, II is equivalent to 2, and XI is equivalent to 11 (X + I). In some cases, a smaller numeral before a larger numeral indicates subtraction (e.g., IV = 4).

Examples

Example 1:

• Input: s = "XLII"
• Output: 42
• Justification: L (50) - X (10) + I (1) + I (1) = 42

Example 2:

• Input: s = "CXCIV"
• Output: 194
• Justification: C (100) - X (10) + C (100) - I (1) + V (5) = 194

Example 3:

• Input: s = "MMMCDXLIV"
• Output: 3444
• Justification: M (1000) + M (1000) + M (1000) - C (100) + D (500) - X (10) + L (50) - I (1) + V (5) = 3444

Constraints:

• 1 <= s.length <= 15
• s contains only the characters ('I', 'V', 'X', 'L', 'C', 'D', 'M').
• It is guaranteed that s is a valid roman numeral in the range [1, 3999].

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