python二叉树递归算法之后序遍历，前序遍历，中序遍历

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Date    : 2016-11-18 08:53:45
# @Author  : why_not_try
# @Link    : http://example.org
# @Version : python 2.7

class Tree(object):
    def __init__(self,data,left,right):
        self.data=data
        self.left=left
        self.right=right
def post_visit(Tree):
    if Tree:
        post_visit(Tree.left)
        post_visit(Tree.right)
        print Tree.data
def pre_visit(Tree):
    if Tree:
        print Tree.data
        pre_visit(Tree.left)
        pre_visit(Tree.right)
def in_visit(Tree):
    if Tree:
        in_visit(Tree.left)
        print Tree.data
        in_visit(Tree.right)
node1=Tree(1,0,0)
node2=Tree(2,0,0)
node3=Tree(3,node1,node2)
node4=Tree(4,0,0)
node5=Tree(5,node4,node3)

print "the post_visit is ....."
post_visit(node5)

print "the pre_visit is......."
pre_visit(node5)

print "the in_visit is ......."
in_visit(node5)

代码很简单，相信一看大部分就能理解。在每一个遍历算法中首先if Tree 为了防止树的左节点或右节点为空时（0代表为空）还去遍历 ，此时程序运行将会报错。

此为node5:

 

运行结果如下：