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
#
class Solution:
    def levelOrder(self, root: TreeNode) -> List[List[int]]:
        if root is None : return []
        queue = [root]
        cur = root
        l_out = []
        while queue :
            l_cur = []
            queue_cur = queue
            queue_next = []
            while queue_cur :
                cur_node = queue_cur.pop(0)
                l_cur.append(cur_node.val)
                if  cur_node.left : queue_next.append(cur_node.left)
                if  cur_node.right : queue_next.append(cur_node.right)
            l_out.append(l_cur)
            queue = queue_next
        return l_out