# 234. Palindrome Linked List
"""
given the head of a signly linked list return true if it is a palindrome or
false otherwise.
"""
# Definition for singly-linked list.
class ListNode(object):
def __init__(self, val=0, next=None):
self.val = val
self.next = next
class Solution(object):
def isPalindrome(self, head):
"""
:type head: ListNode
:rtype: bool
"""
slow, fast, prev = head, head, None
while fast and fast.next:
slow, fast = slow.next, fast.next.next
prev, slow, prev.next = slow, slow.next, None
while slow:
slow.next, prev, slow = prev, slow, slow.next
fast, slow = head, prev
while slow:
if fast.val != slow.val:
return False
fast, slow = fast.next, slow.next
return True
if __name__ == "__main__":
obj = Solution()
h1 = ListNode()
h2 = ListNode()
