[LeetCode] 680. Valid Palindrome II

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

题目大意

能否 最多删除一个字符使原字符串 变为 回文串。

思路

双指针i,j，左右对比字符串元素，若某元素不同，那么判断 i,j-1 或 i+1,j 是否为 回文串。

class Solution {
    public boolean isPalindrome(String s,int i ,int j){
        for(;i<j;i++,j--)
            if(s.charAt(i)!=s.charAt(j))
                return false;
        return true;
    }
    public boolean validPalindrome(String s) {
        for(int i=0,j = s.length()-1;i<j;i++,j--)
            if(s.charAt(i)!=s.charAt(j))
                return isPalindrome(s,i,j-1) || isPalindrome(s,i+1,j);
        return true;
    }
}