palindrome.py

import re

"""
               Head=1
               |
               | __________Tail=[2,3,4,5]
               ||
              [1,2,3,4,5]
[1,2,3,4]=Init________||
                       |
                       |
                  5=Last
"""
def palindrome(data: str):
    # remove all non-alphanumeric from input data
    # and become it lowercase
    # https://docs.python.org/3/howto/regex.html
    # ex: 'Rotor %$#' -> 'rotor'
    data = re.sub(r'\W+', '', data).lower()

    # checks if first (head) and last (last) letter is the same
    # ex: 'r' == 'r'
    eq = data[0] == data[-1]
    # ex: 'rotor' -> 'oto'
    mid = data[1:-1]

    # if has mid, checks if head and last is the same
    # and check the rest (mid), if there it
    if mid:
        # just to know how the recursion works
        # ex: palindrome('rotor') -> palindrome('oto') -> palindrome('t')
        return eq & palindrome(mid)

    return eq


if __name__ == '__main__':
    # if nothing is printed when you try it on terminal, it's means that works
    assert(True == palindrome('Rotor'))
    assert(True == palindrome('Racecar'))
    assert(True == palindrome('Arara'))
    assert(True == palindrome('my gym'))
    assert(True == palindrome('Red rum, sir, is murder'))
    assert(False == palindrome('Lincoln'))

>>> 'rotor'[1:-1]
'oto'
>>> 'oto'[1:-1]
't'
>>> 't'[1:-1]
''