# 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

```java
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;
    }
}
```


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