Python Program to Create a Mirror Copy of a Tree and Display using BFS Traversal

PythonServer Side ProgrammingProgramming

When it is required to create a mirror copy of a tree, and display it using breadth first search, a binary tree class is created with methods set the root element, insert element to left, insert element to right, search for a specific element, and perform post order traversal and so on. An instance of the class is created, and it can be used to access the methods.

Below is the demonstration of the same −

Example

 Live Demo

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

Output

Menu (this assumes no duplicate keys)
insert <data> at root
insert <data> left of <data>
insert <data> right of <data>
mirror
quit
What operation would you do ? insert 6 at root
What operation would you do ? insert 9 left of 6
What operation would you do ? insert 4 right of 6
What operation would you do ? mirror
Creating a mirror copy...
The breadth first search traversal of original tree is :
6 9 4
The breadth first traversal of mirror is :
6 4 9
What operation would you do ?quit
Use quit() or Ctrl-D (i.e. EOF) to exit

Explanation

  • The ‘BinaryTree_struct’ class with required attributes is created.

  • It has an ‘init’ function that is used to assign the left and right nodes to ‘None’.

  • A ‘set_root’ method is defined that helps assign a root node to a value.

  • It has an ‘insert_to_left’ method that helps add elements to the left node of the tree.

  • It has an ‘insert_to_right’ method that helps add elements to the right nodes of the tree.

  • It has a ‘bfs’ method that helps perform breadth first search traversal on the tree.

  • A method named ‘search_elem’ is defined, that helps search for a specific element.

  • It has a ‘copy_mirror’ method that helps create a copy of the binary tree.

  • An instance is created and assigned to ‘None’.

  • The user input is taken for the operation that needs to be performed.

  • Depending on the user’ choice, the operation is performed.

  • Relevant output is displayed on the console.

raja
Updated on 16-Apr-2021 12:34:24

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