LeetCode 234.回文链表
234. 回文链表
Difficulty: 简单
请判断一个链表是否为回文链表。
示例 1:
输入: 1->2
输出: false
示例 2:
输入: 1->2->2->1
输出: true
进阶:
你能否用 O(n) 时间复杂度和 O(1) 空间复杂度解决此题?
Solution
Language: ****
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
def isPalindrome(self, head: ListNode) -> bool:
slow = fast = head
while fast and fast.next:
slow = slow.next
fast = fast.next.next
y = None
while slow:
nxt = slow.next
slow.next = y
y = slow
slow = nxt
while y:
if y.val != head.val:
return False
head = head.next
y = y.next
return True