Check Whether a Linked List Is a Palindrome

# Check Whether a Linked List Is a Palindrome Given the `head` of a singly linked list, return whether its node values read the same from the beginning and the end. ### Function `bool isPalindrome(ListNode* head)` Each existing `ListNode` contains an integer `val` and a pointer `next`. The function receives the list itself, not an array wrapper. ### Example 1 ```text Input: head = [4,7,7,4] Output: true ``` The outer values are both `4`, and the inner values are both `7`. ### Example 2 ```text Input: head = [3,1,3,2] Output: false ``` The first and last values differ. ### Constraints - The list contains between `1` and `100000` nodes. - `0 <= Node.val <= 9`. ### Clarifications Arrays in the examples describe values encountered by following `next` pointers. A single-node list is a palindrome. Return a boolean; do not return a reordered list or newly allocated substitute nodes. ### What a Strong Answer Covers - Correct comparisons for both odd and even list lengths. - The behavior for a single node and an early mismatch. - Auxiliary storage and any changes the implementation makes to input links. ### Follow-up Questions Can you solve the task in `O(n)` time using `O(1)` auxiliary space?