Check if a String Is a Palindrome (and Variants)

Question

## Problem

Check whether a string is a palindrome, then the 'valid palindrome after removing at most one char' variant.

## Example
```
"aba" -> true; "abca" -> true (remove c)
```

## Constraints
- 1 ≤ |s| ≤ 10^5

## Approach
Two pointers; on mismatch try skipping either side. Reported Akamai question.