0680. Valid Palindrome II

https://leetcode.com/problems/valid-palindrome-ii

Description

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.

ac

class Solution {
    public boolean validPalindrome(String s) {
        // edge case
        if (s == null || s.length() == 0) return false;

        int l = 0, r = s.length()-1;
        while (l < r) {
            if (s.charAt(l) != s.charAt(r)) {
                return validate(s, l, r-1) || validate(s, l+1, r);
            }
            l++;
            r--;
        }

        return true;
    }

    private boolean validate(String s, int l, int r) {
        // exit
        if (l > r) return false;
        if (l == r) return true;

        while (l < r) {
            if (s.charAt(l) != s.charAt(r)) return false;
            l++;
            r--;
        }

        return true;
    }
}