本篇是实现二叉树的三种遍历，先序遍历，中序遍历，后序遍历

#!/usr/bin/python# -*- coding: utf-8 -*-class TreeNode(object):    def __init__(self,data=0,left=0,right=0):        self.data = data        self.left = left        self.right = rightclass BTree(object):    def __init__(self,root=0):        self.root = root    def is_empty(self):        if self.root is 0:            return True        else:            return False    def preOrder(self,treenode):        if treenode is 0:            return        print treenode.data        self.preOrder(treenode.left)        self.preOrder(treenode.right)    def inOrder(self,treenode):        if treenode is 0:            return        self.inOrder(treenode.left)        print treenode.data        self.inOrder(treenode.right)    def postOrder(self,treenode):        if treenode is 0:            return        self.postOrder(treenode.left)        self.postOrder(treenode.right)        print treenode.datan1 = TreeNode(data=1)n2 = TreeNode(2,n1,0)n3 = TreeNode(3)n4 = TreeNode(4)n5 = TreeNode(5,n3,n4)n6 = TreeNode(6,n2,n5)n7 = TreeNode(7,n6,0)n8 = TreeNode(8)root = TreeNode('root',n7,n8)bt = BTree(root)print 'preOrder......'print bt.preOrder(bt.root)print 'inOrder......'print bt.inOrder(bt.root)print 'postOrder.....'print bt.postOrder(bt.root)

结果：

preOrder......

root

7

6

2

1

5

3

4

8

inOrder......

1

2

6

3

5

4

7

root

8

postOrder.....

1

2

3

4

5

6

7

8

root