Is Linked List Palindrome

Check if a linked list is a palindrome

from shared.linked_list import LinkedList
from shared.node import Node
from shared.reversed_linked_list import RLinkedList


def is_linked_list_palindrome(linked_list: LinkedList):
    """
    Check if a linked list is a palindrome
    """

    if linked_list is None:
        return True
    current = linked_list.node
    r_linked_list = RLinkedList()
    while current is not None:
        r_linked_list.add(Node(current.data))
        current = current.next

    for i, j in zip(r_linked_list, linked_list):
        if i.data != j.data:
            return False
    return True


if __name__ == "__main__":
    l1 = LinkedList()
    l1.add(Node(1))
    l1.add(Node(0))
    l1.add(Node(5))
    l1.add(Node(0))
    l1.add(Node(1))
    assert is_linked_list_palindrome(l1)

    l2 = LinkedList()
    l2.add(Node(1))
    assert is_linked_list_palindrome(l2)

    l3 = LinkedList()
    l3.add(Node(1))
    l3.add(Node(2))
    l3.add(Node(3))
    assert is_linked_list_palindrome(l3) == False

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Updated on 2021-09-09