README.md

680. Valid Palindrome II

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'.

Note:

1. The string will only contain lowercase characters a-z. The maximum length of the string is 50000.

Solutions (Python)

1. Two Pointers

class Solution:
    def validPalindrome(self, s: str) -> bool:
        def isPalindrome(l: int, r: int) -> bool:
            return all(s[l + i] == s[r - i] for i in range((r - l + 1) // 2))

        l, r = 0, len(s) - 1
        while l < r:
            if s[l] != s[r]:
                return isPalindrome(l + 1, r) or isPalindrome(l, r - 1)

            l += 1
            r -= 1

        return True