题解 | #求二叉树的层序遍历#

用deque数据结构

from collections import deque
class Solution:
    def levelOrder(self , root ):
        # write code here
        if not root:
            return None
        q = deque([])
        q.append(root)
        res = []
        while q:
            size = len(q)
            temp = []
            for i in range(size):
                curr = q.popleft()
                temp.append(curr.val)
                if curr.left:
                    q.append(curr.left)
                if curr.right:
                    q.append(curr.right)

            res.append(temp)
        return res