#coding:utf-8
#二叉樹的遍歷
#簡單的二叉樹節(jié)點類
class Node(object):
    def __init__(self,value,left,right):
        self.value = value
        self.left = left
        self.right = right

#中序遍歷:遍歷左子樹,訪問當前節(jié)點,遍歷右子樹

def mid_travelsal(root):
    if root.left is None:
        mid_travelsal(root.left)
    #訪問當前節(jié)點
    print(root.value)
    if root.right is not None:
        mid_travelsal(root.right)

#前序遍歷:訪問當前節(jié)點,遍歷左子樹,遍歷右子樹

def pre_travelsal(root):
    print (root.value)
    if root.left is not None:
        pre_travelsal(root.left)
    if root.right is not None:
        pre_travelsal(root.right)

#后續(xù)遍歷:遍歷左子樹,遍歷右子樹,訪問當前節(jié)點

def post_trvelsal(root):
    if root.left is not None:
        post_trvelsal(root.left)
    if root.right is not None:
        post_trvelsal(root.right)
    print (root.value)