Leetcode Palindrome list

Give you the head node of a single linked list head , Please judge whether the linked list is a palindrome linked list . If it is , return true ; otherwise , return false .

Example 1：

Input ：head = [1,2,2,1]
Output ：true

Example 2：

Input ：head = [1,2]
Output ：false

Tips ：

• The number of nodes in the linked list is in the range [1, 105] Inside

• 0 <= Node.val <= 9

author ： Power button (LeetCode)
link ：https://leetcode.cn/leetbook/read/top-interview-questions-easy/xnv1oc/
source ： Power button （LeetCode）
The copyright belongs to the author . Commercial reprint please contact the author for authorization , Non-commercial reprint please indicate the source .

Stack First in, then out

The first reaction when you see the palindrome substring is the stack . First, put all elements on the stack . Then compare the stack with the original linked list nodes in turn , For the same True, The difference is False.

class Solution:
    def isPalindrome(self, head: ListNode) -> bool:
        """ Stack """
        stack = list()  #  Create a stack 
        h = head
        while h:
            stack.append(h) #  All linked list elements are put on the stack 
            h = h.next
        n1 = head 
        while stack:
            n2 = stack.pop()  #  Out of the stack 
            if n1.val != n2.val:
                return False
            n1 = n1.next
        return True

You can see that it takes a long time .