Valid Palindrome

Description

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

Note: For the purpose of this problem, we define empty string as valid palindrome.

Example 1:

Input: "A man, a plan, a canal: Panama"
Output: true

Example 2:

Input: "race a car"
Output: false

 

Constraints:

• s consists only of printable ASCII characters.

Solution(javascript)

/*
 * @lc app=leetcode id=125 lang=javascript
 *
 * [125] Valid Palindrome
 */

// @lc code=start
/**
 * @param {string} s
 * @return {boolean}
 */
const isPalindrome = function (s) {
  let newS = ''
  for (const c of s) {
    if (/[a-zA-Z0-9]/.test(c)) {
      newS += c.toLowerCase()
    }
  }
  for (let i = 0; i < Math.floor(newS.length / 2); i++) {
    if (newS[i] !== newS[newS.length - 1 - i]) {
      return false
    }
  }
  return true
}
// @lc code=end