【694】Python实现二叉树

参考：二叉树的创建及遍历(Python版)

几种遍历方式解读，所谓顺序就是根节点出现的位置！

• 先序遍历：中左右

• 中序遍历：左中右

• 后序遍历：左右中

代码如下：

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class BTNode(object):     def __init__(self, key=None, lchild=None, rchild=None):         self.key = key         self.lchild = lchild         self.rchild = rchild   class BiTree(object):     def __init__(self, data_list):         #初始化即将传入的列表的迭代器         self.it = iter(data_list)       def createBiTree(self, bt=None):            try:             #步进获取下一个元素             next_data = next(self.it)             #如果当前列表元素为'#', 则认为其为 None             if next_data == "#":                 bt = None             else:                 bt = BTNode(next_data)                 bt.lchild = self.createBiTree(bt.lchild)                 bt.rchild = self.createBiTree(bt.rchild)         except Exception as e:             print(e)           return bt           #先序遍历函数     def preOrderTrave(self, bt):         if bt is not None:             print(bt.key, end=" ")             self.preOrderTrave(bt.lchild)             self.preOrderTrave(bt.rchild)       #中序遍历函数     def inOrderTrave(self, bt):         if bt is not None:             self.inOrderTrave(bt.lchild)             print(bt.key, end=" ")             self.inOrderTrave(bt.rchild)       #后序遍历函数     def postOrderTrave(self, bt):         if bt is not None:             self.postOrderTrave(bt.lchild)             self.postOrderTrave(bt.rchild)             print(bt.key, end=" ")       #综合打印     def printTrave(self, bt):         print("先序遍历: ", end="")         self.preOrderTrave(bt)         print('\n')         print("中序遍历: ", end="")         self.inOrderTrave(bt)         print('\n')         print("后序遍历: ", end="")         self.postOrderTrave(bt)         print('\n')     data = input("Please input the node value: ") data_list = list(data)   btree = BiTree(data_list) root = btree.createBiTree() btree.printTrave(root)