Python构建二叉树

Question

我在尝试用Python构建二叉树，请问下列程序有哪些问题

class Node(object):
    def __init__(self, data=None, lchild=None, rchild=None):
        self.elem = data  # 表示数据域
        self.lchild = lchild  # 表示左子树
        self.rchild = rchild  # 表示右子树

    def PreOrder(self, root):  # 先序遍历
        if root == None:
            return
        print(root.elem)
        self.PreOrder(root.lchild)  
        self.PreOrder(root.rchild)  

    def InOrder(self, root):  # 中序遍历
        if root == None:
            return
        self.InOrder(root.lchild)  
        print(root.elem)
        self.InOrder(root.rchild)  

    def PostOrder(self, root):  # 后序遍历
        if root == None:
            return
        self.PostOrder(root.lchild)  
        self.PostOrder(root.rchild)  
        print(root.elem)

    def breath_travel(self, root):  # 层序遍历
        if root == None:
            return
        queue = []
        queue.append(root)
        while queue:
            node = queue.pop(0)
            print(node.elem)
            if node.lchild != None:
                queue.append(node.lchild)
            if node.rchild != None:
                queue.append(node.rchild)

    def createBiTree(self, root):
        data = input()
        if data == "#":  # 如果当前元素为'#'，则认为其为None
            return
        else:
            root.elem = data
            root.lchild = self.createBiTree(root.lchild)  # 构造左子树
            root.rchild = self.createBiTree(root.rchild)  # 构造右子树
        return


root = Node()  # 创建根节点
root.createBiTree(root)  # 构造整个二叉树

# 遍历二叉树
root.PreOrder(root)  # 先序遍历
root.InOrder(root)  # 中序遍历
root.PostOrder(root)  # 后序遍历
root.breath_travel(root)  # 层序遍历

Answer 1

最后构造二叉树那里需要改下

            root.lchild = self.createBiTree(Node())  # 构造左子树
            root.rchild = self.createBiTree(Node())  # 构造右子树
        return root