https://leetcode-cn.com/problems/n-ary-tree-level-order-traversal/
题目描述
给定一个 N 叉树，返回其节点值的层序遍历。 (即从左到右，逐层遍历)。
例如，给定一个 3叉树 :
返回其层序遍历:
[
[1],
[3,2,4],
[5,6]
]
说明:
树的深度不会超过 1000。
树的节点总数不会超过 5000。
代码实现
"""
# Definition for a Node.
class Node:
def __init__(self, val=None, children=None):
self.val = val
self.children = children
"""
class Solution:
def levelOrder(self, root: 'Node') -> List[List[int]]:
if root is None:
return []
result = []
previous_layer = [root]
while previous_layer:
current_layer = []
result.append([])
for node in previous_layer:
result[-1].append(node.val)
current_layer.extend(node.children)
previous_layer = current_layer
return result