题解 | #求二叉树的层序遍历#

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param root TreeNode类 
# @return int整型二维数组
#
from queue import deque
class Solution:
    def levelOrder(self , root: TreeNode) -> List[List[int]]:
        # write code here
        res = []
        if not root:
            return res
        queue = deque([root])
        while queue:
            current = []
            for i in range(len(queue)):
                left = queue.popleft()
                current.append(left.val)
                if left.left:
                    queue.append(left.left)
                if left.right:
                    queue.append(left.right)
            res.append(current)
        return res