easyLinked ListTwo Pointers 0 views

Palindrome Linked List

Check whether the values in a singly-linked list read the same forwards and backwards.

Given the head of a singly-linked list, determine whether the sequence of values it contains forms a palindrome -- that is, whether the list reads the same from front to back as it does from back to front.

Return true if the list is a palindrome, or false otherwise.

Example 1

Input: head = [1,2,2,1]

Output: true

Example 2

Input: head = [1,2]

Output: false

Example 3

Input: head = [1]

Output: true

Explanation: A single node is trivially a palindrome.

Constraints

The number of nodes in the list is in the range [0, 100000].
0 <= Node.val <= 9

Follow-up

Can you solve it in O(n) time and O(1) space, without copying the values into another data structure?

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class Solution {
    public boolean isPalindrome(ListNode head) {
        // your code here
        return false;
    }
}

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