Valid Palindrome

Statement

Write a function that takes a string, s, as an input and determines whether or not it is a palindrome.

Note: A palindrome is a word, phrase, or sequence of characters that reads the same backward as forward.

Constraints:

• $1 \leq$ s.length $\leq 2 \times 10^5$
• The string s will contain English uppercase and lowercase letters, digits, and spaces.