680. Valid Palindrome II

Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome.

Example 1:

Input: "aba" Output: True

Example 2:

Input: "abca" Output: True Explanation: You could delete the character 'c'.

Note:

1. The string will only contain lowercase characters a-z. The maximum length of the string is 50000.

class Solution {

    public boolean validPalindrome(String s) {

        int l = 0;

        int r = s.length() - 1;

        while (l < r) {

            if (s.charAt(l) != s.charAt(r))

                return isPalindrome(s, l, r - 1) || isPalindrome(s, l + 1, r); //如果出现不想同的情况，开始处加一或者末尾减一                                                                                

            l++;

            r--;

        }

        return true;

        

    }

    

    private boolean isPalindrome(String s, int start, int end) { //判断是不是回文序列

        while (start < end) {

            if (s.charAt(start) == s.charAt(end)) {

                start++;

                end--;

            }

            else 

                return false;            

        }

        return true;

    }

}