Palindrome Check | Dataford Interview Questions

Dell PowerStore asset labels are checked for mirrored identifiers during a validation workflow. Given a string label, determine whether it is a palindrome after ignoring letter case and all non-alphanumeric characters.

A palindrome reads the same from left to right and right to left after normalization. For example, "A man, a plan, a canal: Panama" is a palindrome because its normalized form is "amanaplanacanalpanama".

Formal Specification

Implement is_palindrome(label).

Input: label, a string containing letters, digits, spaces, and punctuation.
Output: Return true if the alphanumeric characters in label, compared case-insensitively, form a palindrome. Otherwise return false.

Use a two-pointer scan. Do not build a separate normalized string.

Constraints

0 <= len(label) <= 100,000
label contains printable ASCII characters
Compare letters case-insensitively
Ignore all non-alphanumeric characters
Do not construct a separate normalized string

Function Signature

def is_palindrome(label):

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