125. Valid Palindrome

class Solution {
    public boolean isPalindrome(String s) {
        s= s.toLowerCase();
        int i=0, j=s.length()-1;
        while(i<j){
            char a = s.charAt(i);
            char b = s.charAt(j);
            if(!(Character.isLetter(a)||Character.isDigit(a))){
                i++;
                continue;
            }
            if(!(Character.isLetter(b)||Character.isDigit(b))){
                j--;
                continue;
            }
           
            if(a!=b)
                return false;
            i++;
            j--;
        }
        return true;
    }
}