Two pointer approach is pretty natural here but the tricky part is what to do when you hit a mismatch.
Use a two-pointer technique starting from both ends, moving inward while characters match. When a mismatch occurs, check if skipping either the left or right character results in a palindrome, allowing at most one removal. Preprocess the string by filtering out non-alphanumeric characters and converting to lowercase.
Pro tip: Clarify edge cases upfront, such as empty strings or strings with only one character, and mention that the solution runs in O(n) time with O(1) extra space (if preprocessing is done in-place or with O(n) space if creating a new string). This shows attention to detail and efficiency.
Confirm that only alphanumeric characters are considered and case is ignored. Preprocess the string by removing non-alphanumeric characters and converting to lowercase.
Set left pointer at the start and right pointer at the end of the preprocessed string.
While left < right, if characters match, move both pointers inward. If they don't match, proceed to check for palindrome by skipping one character.
When a mismatch occurs, check if the substring from left+1 to right is a palindrome OR the substring from left to right-1 is a palindrome. If either is true, return true; otherwise, return false.
If the loop completes without mismatches, return true. If a mismatch was found and neither skip works, return false.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.