PalindromeLinkedList.py

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution1:
    def isPalindrome(self, head: ListNode) -> bool:
        temp = head
        stack = []
        l = 0
        while temp:
            l += 1
            temp = temp.next
        temp = head
        for i in range(0, l//2):
            stack.append(temp.val)
            temp = temp.next
        if l % 2 != 0:
            temp = temp.next
        for i in range(0, l//2):
            if temp.val == stack.pop():
                continue
            return False
        return True

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution2:
    def isPalindrome(self, head: ListNode) -> bool:
        el = []
        while head:
            el.append(head.val)
            head = head.next
        for i in range(0, len(el)//2):
            if not el[i] == el[-i-1]:
                return False
        return True