📅  最后修改于: 2022-03-11 14:47:13.054000             🧑  作者: Mango
class Node:
def __init__(self,key):
self.left = None
self.right = None
self.val = key
root = Node(1)
root.left = Node(2);
root.right = Node(3);
root.left.left = Node(4);