BST python

class Tree:

  def __init__(self,data):

    self.data = data

    self.left = None

    self.right = None

 

  def is_empty(self):

    return self.data is None

 

  def insert(self,value):

    if value < self.data:

      if self.left is None :

        self.left = Tree(value)

      else:

        self.left.insert(value)

   

    if value > self.data :

      if self.right is None:

        self.right = Tree(value)

      else:

        self.right.insert(value)

       

  def show_left(self):

    current = self.left

    while current:

      if current.data != None:

        print(current.data)

      current = current.left

    print()

   

  def show_right(self):

    current = self.right

    while current:

      if current.data != None:

        print(current.data)

      current = current.right

    print()

   

def delete(root):

  value=-3

  if root:

    delete(root.left)

    delete(root.right)

    if root.data == value and root.data != None:

      root.data = None

     

     

def preorder(root):

  if root and root.data != None:

    print(root.data)

    preorder(root.left)

    preorder(root.right)

def postorder(root):

  if root and root.data != None:

    postorder(root.left)

    postorder(root.right)

    print(root.data)

def inorder(root):

  if root and root.data != None:

    inorder(root.left)

    print(root.data)

    inorder(root.right)

   

   

   

   

root = Tree(1)

root.insert(2)

root.insert(3)

root.insert(4)

root.insert(-1)

root.insert(-2)

root.insert(-3)

root.show_left()

root.show_right()

delete(root)

root.show_right()

root.show_left()

preorder(root)

postorder(root)

inorder(root)