Validating Roman Numerals - Hacker Rank Solution

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  and  (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.

https://developers.google.com/edu/python/regular-expressions

Validating Roman Numerals - Hacker Rank Solution

We can use the regular expression: ^M{0,3}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$.

import re
print bool(re.search(r"^M{0,3}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$",raw_input()))