Python, with its robust string handling capabilities, offers several straightforward ways to determine if a string is a palindrome. These methods range from basic string manipulation to more sophisticated algorithmic approaches.
Basic Method: Reversing a String
The simplest way to check for a palindrome is to reverse the string and compare it with the original.
Example:
def is_palindrome(s):
# Remove non-alphanumeric characters and convert to lowercase
cleaned_s = ''.join(char.lower() for char in s if char.isalnum())
return cleaned_s == cleaned_s[::-1]
print(is_palindrome("A man, a plan, a canal, Panama"))
Using a Loop
A more manual approach involves comparing characters from each end of the string moving towards the center.
Example:
def is_palindrome(s):
cleaned_s = ''.join(char.lower() for char in s if char.isalnum())
left, right = 0, len(cleaned_s) - 1
while left < right:
if cleaned_s[left] != cleaned_s[right]:
return False
left, right = left + 1, right - 1
return True
print(is_palindrome("No lemon, no melon"))
Recursive Method
For those who prefer a recursive approach, palindrome checking can be performed by recursively comparing characters while slicing the string.
Example:
def is_palindrome(s):
def check_palindrome(cleaned_s):
if len(cleaned_s) <= 1:
return True
if cleaned_s[0] != cleaned_s[-1]:
return False
return check_palindrome(cleaned_s[1:-1])
cleaned_s = ''.join(char.lower() for char in s if char.isalnum())
return check_palindrome(cleaned_s)
print(is_palindrome("Was it a car or a cat I saw?"))
