[leetcode]680. Valid Palindrome II有效回文II(可至多删一原字符)

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'.

思路：

代码：

 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)){
                 // try to delete a left side char || delete a right side char
                 return isPalin(s, l+1,r) || isPalin(s, l,r-1);
             }else{
                 l++;
                 r--;
             }
         }
         return true;

     }

    // helper function to judge valid palindrome
    private boolean isPalin(String s , int l, int r){
        while(l < r){
            if(s.charAt(l++)!=s.charAt(r--)) return false;
        }
        return true;
    }
 }