class Node:
   def __init__(self, data):
      self.data = data
      self.next = None

class my_linked_list:
   def __init__(self):
      self.head = None
      self.last_node = None

   def add_value(self, my_data):
      if self.last_node is None:
         self.head = Node(my_data)
         self.last_node = self.head
      else:
         self.last_node.next = Node(my_data)
         self.last_node = self.last_node.next

   def print_it(self):
      curr = self.head
      while curr:
         print(curr.data)
         curr = curr.next

   def alternate_nodes(self):
      self.alternate_helper_fun(self.head)

   def alternate_helper_fun(self, curr):
      if curr is None:
         return
      print(curr.data, end = ' ')
      if curr.next:
         self.alternate_helper_fun(curr.next.next)

my_instance = my_linked_list()
my_list = input("输入链表的元素:").split()
for elem in my_list:
   my_instance.add_value(elem)
print("链表中的替代元素为 :")
my_instance.alternate_nodes()

输入链表的元素 :78 56 34 52 71 96 0 80
链表中的替代元素为 :
78 34 71 0