How hard is LeetCode 680. Valid Palindrome II?

LeetCode 680. Valid Palindrome II is rated Easy on LeetCode.

What is the time complexity of LeetCode 680. Valid Palindrome II?

The Python solution on this page runs in O(n), where n is the length of the string s.

What is the space complexity of LeetCode 680. Valid Palindrome II?

The Python solution on this page uses O(1) auxiliary space.

What topics does LeetCode 680. Valid Palindrome II cover?

LeetCode 680. Valid Palindrome II is tagged Greedy, Two Pointers and String on LeetCode.

Valid Palindrome II — LeetCode 680 Python Solution

EasyGreedyTwo PointersString

Problem: #680
Pattern: Two Pointers
Reading time: 3 min
Source: leetcode.com

The problem

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

Example

Input: s = "aba"
Output: true

Python solution

Python

class Solution:
    def validPalindrome(self, s: str) -> bool:
        def check(i, j):
            while i < j:
                if s[i] != s[j]:
                    return False
                i, j = i + 1, j - 1
            return True

        i, j = 0, len(s) - 1
        while i < j:
            if s[i] != s[j]:
                return check(i, j - 1) or check(i + 1, j)
            i, j = i + 1, j - 1
        return True

Complexity

Measure	Complexity
Time	O(n), where n is the length of the string s
Space	O(1) auxiliary

Pattern: Two Pointers

Use the order already in the input to discard half the search space at every step. LeetCode 680. Valid Palindrome II is filed here because LeetCode tags it Two Pointers, which is the vocabulary this hub collects.

The two pointers guide has the Python template for the pattern and the 201 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 680. Valid Palindrome II?: LeetCode 680. Valid Palindrome II is rated Easy on LeetCode.
What is the time complexity of LeetCode 680. Valid Palindrome II?: The Python solution on this page runs in O(n), where n is the length of the string s.
What is the space complexity of LeetCode 680. Valid Palindrome II?: The Python solution on this page uses O(1) auxiliary space.
What topics does LeetCode 680. Valid Palindrome II cover?: LeetCode 680. Valid Palindrome II is tagged Greedy, Two Pointers and String on LeetCode.