题解 | #求二叉树的层序遍历#

关注python中queue的用法

import queue

class Solution:
    def levelOrder(self , root: TreeNode) -> List[List[int]]:
        # write code here
        res = []
        if not root:
            return res
        q = queue.Queue()
        q.put(root)
    
        while not q.empty():
            q_len = q.qsize()
            res_q = []
            for _ in range(q_len):
                temp = q.get()
                res_q.append(temp.val)
                if temp.left:
                    q.put(temp.left)
                if temp.right:
                    q.put(temp.right)
            res.append(res_q)
        return res