Leetcode 234 Palindrome Linked List

# Definition for singly-linked list.
 class ListNode:
     def __init__(self, x):
         self.val = x
         self.next = None
        

    def isPalindrome(self, head: ListNode) -> bool:
        fast = head
        slow = head

        #orta elemanı bulalım(slow)
        while fast and fast.next:
            fast = fast.next.next
            slow = slow.next

        #2. parçayı terse çevir
        prev = None
        while slow:
            tmp = slow.next
            slow.next = prev
            prev = slow
            slow = tmp
        #palindrome kontrol edelim
        left,right = head,prev
        while right:
            if left.val != right.val:
                return False
            left = left.next
            right = right.next
        return True