python实现二叉树以及二叉树的遍历--1（函数实现）

#定义叶子节点

class TreeNode(object):

    def __init__(self,data,left= None,right= None):

        self.data = data

        self.left = left
        self.right = right

a=TreeNode(3)

b=TreeNode(4)

c=TreeNode(5)

d=TreeNode(6)

#c.right=d

a.left=b

a.right=c

#print a.right.data

print b.left

def pre_travel(node):

     if not node:

        return

     print node.data

     pre_travel(node.left)

     pre_travel(node.right)

     

'''  中序遍历    '''

def mid_travel( node):

    if not node :

        return

    mid_travel(node.left)

    print node.data

    mid_travel(node.right)

'''         

后序遍历

'''

def after_travel(node):

    if not node:

        return

    after_travel(node.left)

    after_travel(node.right)

    print node.data

pre_travel(a)

print '----------------'

mid_travel(a)

print '----------------'

after_travel(a)