Question

Write a recursive version of the palindrome function. It should ignore non-letters and case. (Hint: use isalpha() .)

The function signature is:

def is_palindrome(s):
    """
    -------------------------------------------------------
    Recursively determines if s is a palindrome. Ignores non-letters and case.
    Use: palindrome = is_palindrome(s)
    -------------------------------------------------------
    Parameters:
        s - a string (str)
    Returns:
        palindrome - True if s is a palindrome, False otherwise (boolean)
    -------------------------------------------------------
    """

Answer 1

def is_palindrome(s):
    """
    -------------------------------------------------------
    Recursively determines if s is a palindrome. Ignores non-letters and case.
    Use: palindrome = is_palindrome(s)
    -------------------------------------------------------
    Parameters:
        s - a string (str)
    Returns:
        palindrome - True if s is a palindrome, False otherwise (boolean)
    -------------------------------------------------------
    """
    if len(s) <= 1:
        return True
    else:
        if not s[0].isalpha():
            return is_palindrome(s[1:])
        elif not s[-1].isalpha():
            return is_palindrome(s[:-1])
        if s[0].lower() != s[len(s) - 1].lower():
            return False
        else:
            return is_palindrome(s[1:-1])