二叉树的创建，遍历 python

用递归实现二叉树的创建和遍历：

#定义节点

class TreeNode(object):

def __init__(self, value=None):

self.data = value

self.leftChild =None

        self.rightChild =None

#前序遍历

def preOrder(T):

if T.data ==None:

return

    print(T.data, end=" ")

preOrder(T.leftChild)

preOrder(T.rightChild)

#中序遍历

def inOrder(T):

if T.data ==None:

return

    inOrder(T.leftChild)

print(T.data, end=' ')

inOrder(T.rightChild)

#后序遍历

def postOrder(T):

if T.data ==None:

return

    postOrder(T.leftChild)

postOrder(T.rightChild)

print(T.data, end=' ')

#创建二叉树，传入树和列表

def creatTree(T, L):

value = L[0]

L.pop(0)

if value =='#':

T =None

    else:

T.data = value

T.leftChild = TreeNode()#将左孩子定义为一棵树

        T.rightChild = TreeNode()#将右孩子定义为一棵树

        print(value, end=' ')

creatTree(T.leftChild, L)

creatTree(T.rightChild, L)

return

l = ['A', 'B', 'C', '#', '#', 'D', 'E', '#', 'G', '#', '#', 'F', '#', '#', '#']

myTree = TreeNode()

creatTree(myTree, l)

print()

preOrder(myTree)

print()

inOrder(myTree)

print()

postOrder(myTree)

# print(i)