python二叉樹遞歸算法之后序遍歷，前序遍歷，中序遍歷

#!/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)

代碼很簡單，相信一看大部分就能理解。在每一個遍歷算法中首先if Tree 為了防止樹的左節點或右節點為空時（0代表為空）還去遍歷 ，此時程序運行將會報錯。

此為node5:

 

運行結果如下：