二叉树的深度优先遍历以及广度优先遍历实现

深度遍历分为先序遍历，中序遍历，以及后序遍历；而深度遍历的方式又分为递归深度遍历和栈深度遍历。
广度优先遍历是层序遍历：
python2.x的实现方式

#!/usr/bin/env python
#coding:utf-8

class TreeNode(object):
	def __init__(self):
		self.data = '#'
		self.lchild = None
		self.rchild = None
		
class Tree(TreeNode):
	def __init__(self):
		self.root = TreeNode()
		self.myQueue = []
		
	#Create a tree
	def create_tree(self,tree):
		data = raw_input('->')
		if data == '#':
			tree = None
		else:
			tree.data = data
			tree.lchild = TreeNode()
			self.create_tree(tree.lchild)
			tree.rchild = TreeNode()
			self.create_tree(tree.rchild)
			
	def visit(self,tree):
		#输入#代表空树
		if tree.data is not '#':
			print str(tree.data)+'\t'
			
	def pre_order(self,tree):
		if tree is not None:
			self.visit(tree)
			self.pre_order(tree.lchild)
			self.pre_order(tree.rchild)
			
	def in_order(self,tree):
		if tree is not None:
			self.in_order(tree.lchild)
			self.visit(tree)
			self.in_order(tree.rchild)
			
	def post_order(self,tree):
		if tree is not None:
			self.post_order(tree.lchild)
			self.post_order(tree.rchild)
			self.visit(tree)
			
	def pre_stack(self,tree):
		if tree == None:
			return
		myStack = []
		none = tree
		while node or myStack:
			while node:
				print node.data
				myStack.append(node)
				node = node.lchild
			node = myStack.pop()
			node = node.rchild
			
	def in_stack(self,tree):
		if tree == None:
			return
		myStack = []
		node = tree
		while node or myStack:
			myStack.append(node)
			node=node.lchild
		node=myStack.pop()
		print node.data
		node=node.rchild
		
	def post_stack(self,tree):
		if tree == None:
			return
		myStack1 = []
		myStack2 = []
		node=tree
		myStack1.append(node)
		while myStack1:
			node = myStack1.pop()
			if node.lchild:
				myStack1.append(node.lchild)
			if node.rchild:
				myStack1.append(node.rchild)
			myStack2.append(node)
		while myStack2:
			print myStack2.pop().data
			
	def level_order(self,tree):
		if tree == None:
			return
		myQueue = []
		node = tree
		myQueue.append(node)
		while myQueue:
			node=myQueue.pop(0)
			print node.data
			if node.lchild:
				myQueue.append(node.lchild)
			if node.rchild:
				myQueue.append(node.rchild)

如果python切换到python3的时候，需要修改几个地方：

#!/usr/bin/env python
#coding:utf-8

class TreeNode(object):
    def __init__(self):
        self.data = '#'
        self.lchild = None
        self.rchild = None

class Tree(TreeNode):
    def __init__(self):
        self.root = TreeNode()
        self.myQueue = []

    #Create a tree
    def create_tree(self,tree):
        data = input('->')
        if data == '#':
            tree = None
        else:
            tree.data = data
            tree.lchild = TreeNode()
            self.create_tree(tree.lchild)
            tree.rchild = TreeNode()
            self.create_tree(tree.rchild)

    def visit(self,tree):
        #输入#代表空树
        if tree.data is not '#':
            print(str(tree.data)+'\t')

    def pre_order(self,tree):
        if tree is not None:
            self.visit(tree)
            self.pre_order(tree.lchild)
            self.pre_order(tree.rchild)

    def in_order(self,tree):
        if tree is not None:
            self.in_order(tree.lchild)
            self.visit(tree)
            self.in_order(tree.rchild)

    def post_order(self,tree):
        if tree is not None:
            self.post_order(tree.lchild)
            self.post_order(tree.rchild)
            self.visit(tree)

    def pre_stack(self,tree):
        if tree == None:
            return
        myStack = []
        none = tree
        while node or myStack:
            while node:
                print (node.data)
                myStack.append(node)
                node = node.lchild
            node = myStack.pop()
            node = node.rchild

    def in_stack(self,tree):
        if tree == None:
            return
        myStack = []
        node = tree
        while node or myStack:
            myStack.append(node)
            node=node.lchild
        node=myStack.pop()
        print(node.data)
        node=node.rchild

    def post_stack(self,tree):
        if tree == None:
            return
        myStack1 = []
        myStack2 = []
        node=tree
        myStack1.append(node)
        while myStack1:
            node = myStack1.pop()
            if node.lchild:
                myStack1.append(node.lchild)
            if node.rchild:
                myStack1.append(node.rchild)
            myStack2.append(node)
        while myStack2:
            print( myStack2.pop().data)

    def level_order(self,tree):
        if tree == None:
            return
        myQueue = []
        node = tree
        myQueue.append(node)
        while myQueue:
            node=myQueue.pop(0)
            print(node.data)
            if node.lchild:
                myQueue.append(node.lchild)
            if node.rchild:
                myQueue.append(node.rchild)