Practice/Meta/Leetcode 234. Palindrome Linked List

Leetcode 234. Palindrome Linked List

CodingMust

Problem

Given the head of a singly linked list, determine whether the values in the list form a palindrome. A palindrome reads the same forwards and backwards.

You need to return true if the linked list is a palindrome, and false otherwise.

Requirements

1. You must work with a singly linked list where each node contains an integer value and a pointer to the next node
2. The solution should verify if the sequence of values forms a palindrome
3. Return a boolean indicating whether the list is palindromic

Constraints

• The number of nodes in the list is in the range [1, 100000]
• Node values are integers in the range [0, 1000000]
• Can you solve this in O(n) time?
• Can you solve this in O(1) space (not counting the recursion stack)?

Examples

Example 1:

Input: head = [1, 2, 2, 1] Output: true Explanation: The list reads the same forwards (1 → 2 → 2 → 1) and backwards (1 → 2 → 2 → 1)

Example 2:

Input: head = [1, 2] Output: false Explanation: Reading forwards gives 1 → 2, but backwards gives 2 → 1

Example 3:

Input: head = [1, 2, 3, 2, 1] Output: true Explanation: This odd-length list is symmetric around the middle element (3)