[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;
   }
}