二叉树的常见遍历方式主要有前序，中序和后序，以及层次遍历（从上到下，从左到右）四种方法。
前、中、后遍历分别顺序如下：
分别通过递归和循环的方式实现（Python）：
# -*- coding:utf-8 -*-
class TreeNode:
def __init__(self, x):
self.val = x
self.left = None
self.right = None
def reConstructBinaryTree(pre, tin):
# write code here
if len(pre) == 0:
return None
if len(pre) == 1:
return TreeNode(pre[0])
else:
node = TreeNode(pre[0])
index = tin.index(pre[0])
node.left = reConstructBinaryTree(pre[1:index + 1], tin[:index])
node.right = reConstructBinaryTree(pre[index + 1:], tin[index + 1:])
return node
def predigui(root):
if root==None:
return
print(root.val)
predigui(root.left)
predigui(root.right)
def prexunhuan(root):
if root==None:
return
node=root
stack=[]
while node or stack:
while node:
print(node.val)
stack.append(node)
node=node.left
node=stack.pop()
node=node.right
pass
def indigui(root):
if not root:
return
indigui(root.left)
print(root.val)
indigui(root.right)
def inxunhuan(root):
if not root:
return
stack=[]
node=root
while stack or node:
while node :
stack.append(node)
node=node.left
node=stack.pop()
print(node.val)
node=node.right
def postdigui(root):
if not root:
return
postdigui(root.left)
postdigui(root.right)
print(root.val)
def postxunhuan(root):
if not root:
return
node=root
stack=[]
stack2=[]
while node or stack:
while node:
stack.append(node)
stack2.append(node)
node=node.right
node=stack.pop()
node=node.left
while stack2:
print(stack2.pop().val)
if __name__=='__main__':
root=reConstructBinaryTree([1,2,4,7,3,5,6,8],[4,7,2,1,5,3,8,6])
#predigui(root)
#prexunhuan(root)
#indigui(root)
#inxunhuan(root)
#postdigui(root)
postxunhuan(root)