LeetCode – 234. Palindrome Linked List

Given a singly linked list, determine if it is a palindrome.

Follow up:
Could you do it in O(n) time and O(1) space?

The difficulty of this question lies in the follow-up.

/** * Definition for singly-linked list. * public class ListNode { * int val; while(head != null){ ListNode n = new ListNode(head.val); n.next = result; result = n; head = head.next; } return result; } public boolean checksame(ListNode a, ListNode b){ while(a != null && b != null){ if(a.val != b.val){ return false; } a = a.next; b = b.next; } return true; } }