LeetCode in TypeScript
125. Valid Palindrome
Easy
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.
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.
Constraints:
1 <= s.length <= 2 * 105sconsists only of printable ASCII characters.
Solution
function isPalindrome(s: string): boolean {
if (s.length < 2) {
return true
}
let sFormated = s.toLowerCase().replace(/[^a-zA-Z0-9]/g, '')
let reversed = sFormated.split('').reverse().join('').replace(',', '')
return sFormated === reversed
}
export { isPalindrome }