【Leetcode】125.验证回文串

输入: "A man, a plan, a canal: Panama"
输出: true

输入: "race a car"
输出: false

class Solution {
    public boolean isPalindrome(String s) {
        if (s == null) return false;
        if (s.length() == 0) return true;
        int i = 0;
        int j = s.length() - 1;
        while (i < j) {
            while (i < j && !Character.isLetterOrDigit(s.charAt(i))) i++;
            while (i < j && !Character.isLetterOrDigit(s.charAt(j))) j--;
            if (Character.toLowerCase(s.charAt(i)) != Character.toLowerCase(s.charAt(j))) return false;
            i++;
            j--;
        }
        return true;
    }
}