Palindrome recursion with whitespace and a function not working

Question

I have a palindrome recursion function, which works for every word except for ones with spaces. How do I fix the code to not take spaces into account?

def ispalindrome(word):
    if len(word) < 2: 
        return True
    if word[0] != word[-1]: 
        return False
    return ispalindrome(word[1:-1])
print(ispalindrome("taco cat"))

Does this answer your question? [How to remove white spaces from a string in Python?](https://stackoverflow.com/questions/20991605/how-to-remove-white-spaces-from-a-string-in-python) — David Buck, Mar 28 '20 at 10:57
Just use word = word.strip() in the first line of the function — Felipe Borges, Mar 28 '20 at 10:57
Remove spaces with `word = word.replace(" ", "")` at the top of your function. — David Buck, Mar 28 '20 at 10:58

score 2 · Answer 1 · answered Mar 28 '20 at 11:00

Simply modify the string so that the whitespace can be gone. one method is using the split join functions of python and the other is the usage of regex.

here's a sample of a running code:

def ispalindrome(word):
    if len(word) < 2: 
        return True
    if word[0] != word[-1]: 
        return False
    return ispalindrome(word[1:-1])

print(ispalindrome(''.join("taco cat".split())))

Output: True

I hope that helps!

Felipe Borges · Answer 2 · 2020-07-06T13:07:58.627

2

Add that line in the function. This will remove white spaces and other tabular information.

def ispalindrome(word):
    word = word.strip() # remote white spaces and tabular information
    if len(word) < 2: 
        return True
    if word[0] != word[-1]: 
        return False
    return ispalindrome(word[1:-1])

edited Jul 06 '20 at 13:07

answered Mar 28 '20 at 11:00

Felipe Borges

405
4
8

score 1 · Answer 3 · 2020-03-28T11:10:33.053

You should remove spaces in string at the beginning of the function, because space is a character too and function check for it too.

def ispalindrome(word):
    word = word.replace(' ', '')
    if len(word) < 2: 
        return True
    if word[0] != word[-1]: 
        return False
    return ispalindrome(word[1:-1])
print(ispalindrome("taco cat"))

There are different ways to remove spaces from string, these are:

1)

string = string.replace(" ", "")

2)

string = "".join(string.split())

3)

import re
pattern = re.compile(r'\s+') 
string = re.sub(pattern, '', string)

4)

import string 
string = string.translate(None, ' \n\t\r')

score 1 · Accepted Answer · answered Nov 13 '21 at 02:55

class Solution:
    def recursive(self,s:str):
        string=''.join(char.lower() for char in s if char.isalnum())
        def dfs(s:str):
            if len(s)<=1:
                return True
            if s[0]==s[-1]:
                #reduce the bigger problem to smaller problem
                return dfs(s[1:-1])
        return dfs(string)

Palindrome recursion with whitespace and a function not working

4 Answers4