125. Valid Palindrome.java

// 125. Valid Palindrome

class Solution {
    public boolean isPalindrome(String s) {
        int left = 0;
        int right = s.length() - 1;
        while (left < right){
            char l = s.charAt(left);
            char r = s.charAt(right);
            if(!Character.isLetterOrDigit(l))
                left++;
            else if(!Character.isLetterOrDigit(r))
                right--;
            else if(Character.toLowerCase(l) != Character.toLowerCase(r))
                return false;
            else {
                right--;
                left++;
            }
        }
        return true;
    }
}