"""
Reverse a Linked List with O(1) space, without using recursion.
"""
import copy
from linked_list import Node
node = Node()
node.insert_at_beginning(1)
node.insert_at_end(2)
node.insert_at_end(3)
node.insert_at_end(4)
node.insert_at_end(5)
prev_node = None
next_node = node.head.next
while (True):
node.head.next = prev_node
if next_node == None:
break
prev_node = node.head
node.head = next_node
next_node = next_node.next
node.print_list()
