Palindrome Check in Python | Dataford Interview Questions

Unisys Stealth components may receive identifiers and labels in inconsistent formatting. Implement a palindrome check that determines whether a text value reads the same forward and backward after ignoring case and non-alphanumeric characters.

Do not use reverse slicing, reversed(), or any built-in palindrome helper. The algorithm should compare characters from both ends and use constant extra space.

Formal Specification

Implement is_palindrome(text), where text is a string. Return True if the normalized text is a palindrome, otherwise return False. Normalization means comparing letters without regard to case and ignoring every character for which isalnum() is false. An empty normalized string is considered a palindrome.

Constraints

0 <= len(text) <= 10^5
text may contain Unicode letters, digits, whitespace, and punctuation
Comparison is case-insensitive
Non-alphanumeric characters are ignored
Do not use reverse slicing, reversed(), or construct another string

Function Signature

def is_palindrome(text):

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