242. Valid Anagram

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 * 10^5
• s consists only of printable ASCII characters.

Answer

func isPalindrome(s string) bool {
    reg, _ := regexp.Compile("[^a-zA-Z0-9]+")
    s =strings.ToLower(reg.ReplaceAllString(s, ""))
    l := 0
    r := len(s) - 1

    for l <= r {
        if s[l] != s[r]{
            return false
        }
        l++
        r--
    }
    return true
}