LeetCode 680. Valid Palindrome II

原题链接在这里：https://leetcode.com/problems/valid-palindrome-ii/description/

题目：

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.

题解：

当出现错位时，或左或右向内移动一位.

Time Complexity: O(s.length()). Space: O(1).

AC Java:

 1 class Solution {
 2     public boolean validPalindrome(String s) {
 3         int l = 0; int r = s.length()-1;
 4         while(l<r){
 5             if(s.charAt(l) != s.charAt(r)){
 6                 return isPalindrome(s, l+1, r) || isPalindrome(s, l, r-1);
 7             }
 8             l++;
 9             r--;
10         }
11         return true;
12     }
13     
14     private boolean isPalindrome(String s, int l, int r){
15         while(l<r){
16             if(s.charAt(l) != s.charAt(r)){
17                 return false;
18             }
19             l++;
20             r--;
21         }
22         return true;
23     }
24 }

跟上Valid Palindrome III.

类似Valid Palindrome.