import queue

class TreeNode:
    def init(self,val=None,left=None,right=None):
        self.val = val
        self.left = left
        self.right = right
        def settag(self,tag=None):
        self.tag = tag
    
    def visit(treenode):
        print(str(treenode.val),end=' ')

    def levelOrder(root):
        deque = queue.Queue()
        if(root is not None):
            deque.put(root)
        while(not deque.empty()):
        treenode = deque.get()
        visit(treenode)
        if(treenode.left is not None):
            deque.put(treenode.left)
        if(treenode.right is not None):
            deque.put(treenode.right)

# 说一下他们的时间复杂度和空间复杂度
#　一般来说，时间复杂度高的算法比复杂度低的算法慢

＃　时间复杂度的最优,最差,和平均值

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