Leetcode 234 回文链表

给你一个单链表的头节点 head ，请你判断该链表是否为 回文链表。如果是，返回 true ；否则，返回 false 。

用一个 nums 数组存起来链表的值，然后双指针判断是否是回文链表。

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def isPalindrome(self, head: Optional[ListNode]) -> bool:
        nums = []
        while head is not None:
            nums.append(head.val)
            head = head.next
        n = len(nums)
        if n == 1 or n == 0:
            return True
        i, j = 0, n-1
        while i <= j:
            if nums[i] == nums[j]:
                i += 1
                j -= 1
                continue
            else:
                return False
        return True