CODE EXAMPLE FOR PYTHON

tree in python

class Node:
     def __init__(self,data):
          self.data = data
          self.parent = None
          self.left = None
          self.right = None

     def __repr__(self):
          return repr(self.data)

     def add_left(self,node):
         self.left = node
         if node is not None:
             node.parent = self

     def add_right(self,node):
         self.right = node
         if node is not None:
             node.parent = self
'''
Example:
          _2_
        /       
       7         9
      /          
     1   6         8
         /        / 
       5   10   3   4
'''
def create_tree():
    two = Node(2)
    seven = Node(7)
    nine = Node(9)
    two.add_left(seven)
    two.add_right(nine)
    one = Node(1)
    six = Node(6)
    seven.add_left(one)
    seven.add_right(six)
    five = Node(5)
    ten = Node(10)
    six.add_left(five)
    six.add_right(ten)
    eight = Node(8)
    three = Node(3)
    four = Node(4)
    nine.add_right(eight)
    eight.add_left(three)
    eight.add_right(four)

    # now return the root node
    return two

def pre_order(node):
    print(node)
    if node.left:
        pre_order(node.left)
    if node.right:
        pre_order(node.right)

def in_order(node):
    if node.left:
        in_order(node.left)
    print(node)
    if node.right:
        in_order(node.right)

def post_order(node):
    if node.left:
        post_order(node.left)
    if node.right:
        post_order(node.right)
    print(node)

if __name__ == "__main__":
    root = create_tree()
    print("
Pre-order traversal:")
    pre_order(root)
    print("
In-order traversal:")
    in_order(root)
    print("
Post-order traversal:")
    post_order(root)