Coding Challenge: Palindrome Checker

A palindrome is a word or phrase that reads the same forwards and backwards. In this challenge, you'll build a program to check if text is a palindrome. This exercise teaches string manipulation, a fundamental programming skill.

The Challenge

Write a Python function that checks if a word or phrase is a palindrome. The function should ignore spaces, punctuation, and be case-insensitive.

Examples:
is_palindrome("radar") → True
is_palindrome("hello") → False
is_palindrome("A man a plan a canal Panama") → True

Rules

Ignore spaces and punctuation. Make it case-insensitive (A == a). Return True or False. Write in Python 3.

Starter Code

def is_palindrome(text):
    # Your code here
    pass

# Test cases
print(is_palindrome("radar"))  # Should print: True
print(is_palindrome("hello"))  # Should print: False

Try solving it yourself before looking at the solution below. The hints might help if you get stuck.

Hints

Solution

def is_palindrome(text):
    # Convert to lowercase
    text = text.lower()
    
    # Remove spaces
    text = text.replace(" ", "")
    
    # Check if equal to reverse
    return text == text[::-1]

# Test
print(is_palindrome("radar"))  # True
print(is_palindrome("hello"))  # False
print(is_palindrome("Race car"))  # True

import re

def is_palindrome(text):
    # Convert to lowercase
    text = text.lower()
    
    # Remove all non-alphanumeric characters
    text = re.sub(r'[^a-z0-9]', '', text)
    
    # Check if equal to reverse
    return text == text[::-1]

# Test with complex examples
print(is_palindrome("A man, a plan, a canal: Panama"))  # True
print(is_palindrome("Was it a car or a cat I saw?"))    # True

How It Works

The [::-1] trick: This is Python's slice notation for reversing. The syntax is [start:end:step], and -1 means go backwards.

Breaking it down: First, convert to lowercase so "Race" and "race" match. Then remove spaces so "race car" becomes "racecar". Finally, reverse it and compare—if they match, it's a palindrome.

Bonus Challenges

Challenge 1: Count palindromes in a list. Given words = ["radar", "hello", "level", "world", "civic"], count how many are palindromes.

Challenge 2: Find the longest palindrome in a string. Given "abacdfgdcaba", find the longest palindromic substring.

Challenge 3: Create a palindrome generator. Turn any word into a palindrome.

def count_palindromes(word_list):
    return sum(1 for word in word_list if is_palindrome(word))

words = ["radar", "hello", "level", "world", "civic"]
print(count_palindromes(words))  # 3

def longest_palindrome(text):
    longest = ""
    for i in range(len(text)):
        for j in range(i + 1, len(text) + 1):
            substring = text[i:j]
            if is_palindrome(substring) and len(substring) > len(longest):
                longest = substring
    return longest

print(longest_palindrome("abacdfgdcaba"))  # "aba"

def make_palindrome(text):
    text = text.lower()
    return text + text[::-1][1:]

print(make_palindrome("cat"))  # "catac"

Share your solution! Post your code in the comments. Bonus points for creative approaches or optimizations.