125. Valid Palindrome (Easy) (https://leetcode.com/problems/valid-palindrome/)
A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers. Given a string s, return true if it is a palindrome, or false otherwise. Constraints: - 1 <= s.length <= 2 * 10^5 - s consists only of printable ASCII characters.
function isPalindrome(s: string): boolean {
const lc = s.toLocaleLowerCase().replace(/[^a-zA-Z\d]/g, "");
return lc === lc.split("").reverse().join("");
}Example 1:
Input: s = "A man, a plan, a canal: Panama"
Output: true
Explanation: "amanaplanacanalpanama" is a palindrome.
Example 2:
Input: s = "race a car"
Output: false
Explanation: "raceacar" is not a palindrome.
Example 3:
Input: s = " "
Output: true
Explanation: s is an empty string "" after removing non-alphanumeric characters.
Since an empty string reads the same forward and backward, it is a palindrome.