剑指offer_二叉树_从上往下打印二叉树

二叉树_从上往下打印二叉树

题目描述
从上往下打印出二叉树的每个节点，同层节点从左至右打印。
问题解析

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回从上到下每个节点值列表，例：[1,2,3]
    def PrintFromTopToBottom(self, root):
        # write code here
        queue = []
        result = []
        if not root:
            return result
        queue.append(root)
        while queue:
            newnode = queue.pop(0)
            result.append(newnode.val)
            if newnode.left:
                queue.append(newnode.left)
            if newnode.right:
                queue.append(newnode.right)
        return result