Palindrome With Cleanup | Dataford Interview Questions

An AstraZeneca data-quality utility receives a free-form study label. Determine whether the label is a palindrome after ignoring letter case and removing all non-alphanumeric characters.

A palindrome reads identically from left to right and right to left after normalization. For this problem, use Python's alphanumeric definition, so str.isalnum() determines whether a character is retained.

Formal Specification

Implement valid_palindrome(s).

Input: s, a string.
Output: Return True if the normalized string is a palindrome, otherwise return False.

Constraints

0 <= len(s) <= 100,000
s may include letters, digits, whitespace, punctuation, and Unicode alphanumeric characters
Case differences must be ignored
The primary solution must use O(1) auxiliary space

Function Signature

def valid_palindrome(s):

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