Palindrome Checking | Dataford Interview Questions

Chevron systems may receive short text labels or inspection codes that need basic structural validation. Given a string, determine whether it reads identically forward and backward after ignoring letter case and all non-alphanumeric characters.

Formal Specification

Implement is_palindrome(s), where s is a string. Return True if the normalized string is a palindrome, otherwise return False.

Normalization means:

Convert uppercase English letters to lowercase.
Keep only characters from a-z and 0-9.
Ignore spaces, punctuation, and other characters.

Use a two-pointer approach that compares characters from both ends. Do not create a second normalized string.

Constraints

1 <= len(s) <= 2 * 10^5
s contains printable ASCII characters
Only English letters and digits are considered alphanumeric
Comparison is case-insensitive

Function Signature

def is_palindrome(s):

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