class BinaryTree_struct:
   def __init__(self, key=None):
      self.key = key
      self.left = None
      self.right = None

   def set_root(self, key):
      self.key = key

   def insert_to_left(self, new_node):
      self.left = new_node

   def insert_to_right(self, new_node):
      self.right = new_node

   def search_elem(self, key):
      if self.key == key:
         return self
      if self.left is not None:
         temp = self.left.search_elem(key)
      if temp is not None:
         return temp
      if self.right is not None:
         temp = self.right.search_elem(key)
         return temp
      return None

   def copy_mirror(self):
      mirror = BinaryTree_struct(self.key)
      if self.right is not None:
         mirror.left = self.right.copy_mirror()
      if self.left is not None:
         mirror.right = self.left.copy_mirror()
      return mirror

   def bfs(self):
      queue = [self]
      while queue != []:
         popped = queue.pop(0)
         if popped.left is not None:
            queue.append(popped.left)
         if popped.right is not None:
            queue.append(popped.right)
         print(popped.key, end=' ')

my_instance = None

print('Menu (this assumes no duplicate keys)')
print('insert <data> at root')
print('insert <data> left of <data>')
print('insert <data> right of <data>')
print('mirror')
print('quit')

while True:
   my_input = input('What operation would you do ? ').split()

   operation = my_input[0].strip().lower()
   if operation == 'insert':
      data = int(my_input[1])
      new_node = BinaryTree_struct(data)
      suboperation = my_input[2].strip().lower()
      if suboperation == 'at':
         my_instance = new_node
      else:
         position = my_input[4].strip().lower()
         key = int(position)
         ref_node = None
         if my_instance is not None:
            ref_node = my_instance.search_elem(key)
         if ref_node is None:
            print('No such key exists..')
            continue
         if suboperation == 'left':
            ref_node.insert_to_left(new_node)
         elif suboperation == 'right':
            ref_node.insert_to_right(new_node)

   elif operation == 'mirror':
      if my_instance is not None:
         print('Creating a mirror copy...')
         mirror = my_instance.copy_mirror()
         print('The breadth first search traversal of original tree is : ')
         my_instance.bfs()
         print()
         print('The breadth first traversal of mirror is : ')
         mirror.bfs()
         print()
   elif operation == 'quit':
      break

Menu (this assumes no duplicate关键字)
在根插入
在左边插入
在右边插入
镜像
退出
你想做什么操作？
插入6到根
在6的左侧插入9
在6的右侧插入4
镜像
创建镜像副本...
原树的广度优先搜索遍历：
6 9 4
镜像的广度优先遍历：
6 4 9
退出