BinaryTree.py

class Node (object):
    def __init__(self, value):
        self.value = value
        self.value = None
        self.value = None


class BinaryTree(object):
    def __init__(self, root):
        self.root = Node(root)

    def print_tree(self, traversal_type):
        if traversal_type == "preorder":
            return self.preorder_print(tree.root, " ")
        elif traversal_type == "inorder":
            return self.inorder_print(tree.root, " ")
        elif traversal_type == "postorder":
            return self.preorder_print(tree.root, " ")
        else:
            print("Traversal type" + str(traversal_type) + "is not supported.")
            return False

    def preorder_print(self, start, traversal):
        '''Root -> Left -> Right'''
        if start:
            traversal += (str(start.value) + '-')
            traversal = self.preorder_print(start.left, traversal)
            traversal = self.preorder_print(start.right, traversal)

        return traversal

    def inorder_print(self, start, traversal):
        '''Left -> Root -> Right'''
        if start:
            traversal = self.inorder_print(start.left, traversal)
            traversal += (str(start.value) + '-')
            traversal = self.inorder_print(start.right, traversal)
        return traversal

    def postorder_print(self, start, traversal):

        '''Left -> Right -> Root'''
        if start:
            traversal = self.inorder_print(start.left, traversal)
            traversal += (str(start.value) + '-')
            traversal = self.inorder_print(start.right, traversal)

        return traversal











# 1-2-4-5-3-6-7
# 4-2-5-1-6-7-3
# 4-2-5-6-3-7-1

#                  1
#               /      \
#              2        3
#             / \      / \
#            4   5    6   7
#

# Set up tree:
tree = BinaryTree(1)
tree.root.left = Node(2)
tree.root.right = Node(3)
tree.root.left.left = Node(4)
tree.root.left.right = Node(5)
tree.root.right.left = Node(6)
tree.root.right.right = Node(7)
#tree.root.right.right.right = Node(8)


print(tree.print_tree("preorder"))