HackerRank Python Solution - Regex and Parsing - Validating Roman Numerals

• You are given a string, and you have to validate whether it's a valid Roman numeral. If it is valid, print True. Otherwise, print False. Try to create a regular expression for a valid Roman numeral.

Input Format:

• A single line of input containing a string of Roman characters.

Output Format:

• Output a single line containing True or False according to the instructions above.

Constraints:

• The number will be between 1 and 3999 (both included).

Sample Input:

CDXXI

Sample Output:

True

References:

• Regular expressions are a key concept in any programming language. A quick explanation with Python examples is available here. You could also go through the link below to read more about regular expressions in Python.

Solution:

regex_pattern = r"^(?=[MDCLXVI])M{0,3}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$"

import re
print(str(bool(re.match(regex_pattern, input()))))

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