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从上往下打印二叉树

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param root TreeNode类 
# @return int整型一维数组
#
from collections import deque
class Solution:def PrintFromTopToBottom(self , root: TreeNode) -> List[int]:# 层序遍历if not root:return []q = deque()q.append(root)res = []while q:node = q.popleft()res.append(node.val)if node.left:q.append(node.left)if node.right:q.append(node.right)return res