LeetCode-680. Valid Palindrome II [C++][Java]

LeetCode-680. Valid Palindrome IIhttps://leetcode.com/problems/valid-palindrome-ii/

题目描述

Given a string s, return true if the s can be palindrome after deleting at most one character from it.

Example 1:

Input: s = "aba"
Output: true

Example 2:

Input: s = "abca"
Output: true
Explanation: You could delete the character 'c'.

Example 3:

Input: s = "abc"
Output: false

Constraints:

• 1 <= s.length <= 105
• s consists of lowercase English letters.

解题思路

【C++】

class Solution {
public:
    bool validPalindrome(string s) {
        int i = 0, j = s.length()-1;
        while(i < j) if(s[i++] != s[j--]) return isPalindrome(s, i, j+1) || isPalindrome(s, i-1, j);
        return true;
    }
    bool isPalindrome(string s, int i, int j) {
        while(i < j) if(s[i++] != s[j--]) return false;
        return true;
    }
};

【Java】

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