二叉树 —— 创建 + 先序、中序、后序遍历（递归+非递归）

#coding:utf-8

class  Node(object):
'''构造节点'''
def __init__(self,data=None,lchild=None,rchild=None):
self.data = data
self.lchild = lchild
self.rchild = rchild

class Tree(object):

def __init__(self):
self.root = Node()

def addNode(self,data):
'''利用队列构造树'''
node = Node(data)
if self.root.data == None:
self.root = node
else:
myqueue =  []
treeNode = self.root
myqueue.append(treeNode)
while myqueue:
treeNode = myqueue.pop(0)
if treeNode.lchild == None:
treeNode.lchild = node
return
elif treeNode.rchild == None:
treeNode.rchild = node
return
else:
myqueue.append(treeNode.lchild)
myqueue.append(treeNode.rchild)

def  xianxu_digui(self,root):
'''利用递归实现先序遍历'''
if root == None:
return root
else:
print(root.data,end=' ')
self.xianxu_digui(root.lchild)
self.xianxu_digui(root.rchild)

def front_stack(self, root):
"""利用栈实现二叉树的先序遍历"""
if root == None:
return
mystack = []
node = root
while node or mystack:
while node:  # 从根节点开始，一直找它的左子树
print(node.data, end=' ')
mystack.append(node)
node = node.lchild
node = mystack.pop()  #
node = node.rchild  #

def zhongxu_digui(self,root):
'''利用递归实现中序遍历'''
if root == None:
return root
else:
self.zhongxu_digui(root.lchild)
print(root.data,end=' ')
self.zhongxu_digui(root.rchild)

def midd_stack(self, root):
'''利用栈实现中序遍历'''
if root == None:
return
mystack = []
node = root
while node or mystack:
while node:
mystack.append(node)
node = node.lchild
node = mystack.pop()
print(node.data, end=' ')
node = node.rchild

def houxu_digui(self,root):
'''利用递归实现后序遍历'''
if root == None:
return
else:
self.houxu_digui(root.lchild)
self.houxu_digui(root.rchild)
print(root.data,end=' ')

def later_stack(self, root):
"""利用栈实现后序遍历"""
if root == None:
return
mystack1 = []  # mystack1 这是一个中介栈，目的是调整进mystack2 栈的顺序。
mystack2 = []  #该栈里面的元素是 逆序的倒序，逐个弹出，访问
node = root
mystack1.append(node)
while mystack1:
node = mystack1.pop()
mystack2.append(node)
if node.lchild:
mystack1.append(node.lchild)
if node.rchild:
mystack1.append(node.rchild)

while mystack2:  # 将mystack2中的元素逐个弹出，即为后序遍历次序
print(mystack2.pop().data,end=' ')

def leve_queue(self,root):
'''按层遍历'''
if root == None:
return
else:
myqueue = []
node = root
myqueue.append(root)
while myqueue:
node = myqueue.pop(0)
print(node.data,end=' ')
if node.lchild:
myqueue.append(node.lchild)
if node.rchild:
myqueue.append(node.rchild)

tree = Tree()
tree.addNode(1)
tree.addNode(2)
tree.addNode(3)
tree.addNode(4)
tree.addNode(5)
tree.addNode(6)
tree.addNode(7)
tree.addNode(8)
tree.addNode(9)
tree.addNode(10)
#
print('先序遍历')
tree.xianxu_digui(tree.root)
print('\n')
tree.front_stack(tree.root)
print('\n')
print('中序遍历 ')
tree.zhongxu_digui(tree.root)
print('\n')
tree.midd_stack(tree.root)
print('\n')
print('后序遍历')
tree.houxu_digui(tree.root)
print('\n')
tree.later_stack(tree.root)
print('\n')
print('层次遍历')
tree.leve_queue(tree.root)