binary_tree.py

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

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

    def add_left(self, node):
        self.left = node

    def add_right(self, node):
        self.right = node

"""
      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)
	nine.add_right(eight)
	three = Node(3)
	four = Node(4)
	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 post_order(node):
	if node.left:
		post_order(node.left)
	if node.right:
		post_order(node.right)
	print(node)


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


if __name__ == "__main__":
	root = create_tree()
	in_order(root)