主要是：前序遍歷、中序遍歷、后序遍歷、層級遍歷、非遞歸前序遍歷、非遞歸中序遍歷、非遞歸后序遍歷

代碼如下:
#!/usr/bin/env python
#-*- coding:utf8 -*-

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

class Tree(object):
    def __init__(self, root=None):
        self.root = None

    def makeTree(self, data, left, right):
        self.root = TreeNode(data, left, right)

    def is_empty(self):
        """是否為空 """
        if self.root is None:
            return True
        return False

    def preOrder(self, r):
        """前序遍歷 """
        if not r.is_empty():
            print r.root.data
            if r.root.left is not None:
                r.preOrder(r.root.left)
            if r.root.right is not None:
                r.preOrder(r.root.right)

    def inOrder(self, r):
        """中序遍歷 """
        if not r.is_empty():
            if r.root.left is not None:
                r.preOrder(r.root.left)
            print r.root.data
            if r.root.right is not None:
                r.preOrder(r.root.right)

    def postOrder(self, r):
        """后續遍歷 """
        if not r.is_empty():
            if r.root.left is not None:
                r.preOrder(r.root.left)
            print r.root.data
            if r.root.right is not None: