Strings & Text

Python Program to Check Palindrome

Check whether a string or integer reads the same forwards and backwards, with case and whitespace sanitization.

Python Source Code

Editable code sample with line numbers

Python

Expected Output

When this program is compiled and executed, the terminal outputs:

"Racecar" -> Palindrome: True
"A man, a plan, a canal: Panama" -> Palindrome: True
"ZenCompiler" -> Palindrome: False
"12321" -> Palindrome: True

Integer tests:
  121 -> Palindrome: True
 -121 -> Palindrome: False
   10 -> Palindrome: False
 1221 -> Palindrome: True

How the Code Works

For strings, we filter non-alphanumeric characters with ch.isalnum() and compare with the reversed slice. For integers, converting to string uses extra memory; is_palindrome_integer reverses half of the integer digits mathematically to avoid memory allocation and overflow.

Time Complexity

O(N) for strings, O(log10 N) for integers

Space Complexity

O(N) for string cleanup, O(1) for math check

Key Takeaways & Best Practices

Alphanumeric filtering is necessary when verifying natural language palindromes.
Reversing only half the integer digits halves execution time and uses zero heap memory.

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