python解法Queue容器实现bfs

#熟悉Queue容器的 的 .put() .get() .empty()用法
# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
import Queue  #python2为import Queue  / python3中为 import queue
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
        if not root:
            return []
        q=Queue.Queue()
        q.put(root)
        res=[]
        while not q.empty():
            node=q.get()
            res.append(node.val)
            if node.left:
                q.put(node.left)
            if node.right:
                q.put(node.right)
        return res