每日5题验证回文串

Posted 2022-01-18 Alice_yufeng

class Solution 
    public boolean isPalindrome(String s) 
        return isPalindromeHelper(s, 0, s.length() - 1);
    

    public boolean isPalindromeHelper(String s, int left, int right) 
        if (left >= right)
            return true;
        while (left < right && !Character.isLetterOrDigit(s.charAt(left)))
            left++;
        while (left < right && !Character.isLetterOrDigit(s.charAt(right)))
            right--;
        return Character.toLowerCase(s.charAt(left)) == Character.toLowerCase(s.charAt(right)) && isPalindromeHelper(s, ++left, --right);