# LeetCode: 429. N-ary Tree Level Order Traversal

## 题目¶

Given an n-ary tree, return the level order traversal of its nodes' values.

Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).

Example 1:

```Input: root = [1,null,3,2,4,null,5,6]
Output: [[1],[3,2,4],[5,6]]
```

Example 2:

```Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: [[1],[2,3,4,5],[6,7,8,9,10],[11,12,13],[14]]
```

Constraints:

• The height of the n-ary tree is less than or equal to 1000
• The total number of nodes is between [0, 10^4]

## 解法¶

```"""
# Definition for a Node.
class Node(object):
def __init__(self, val=None, children=None):
self.val = val
self.children = children
"""

class Solution(object):
def levelOrder(self, root):
if root is None:
return []

values = []
children = [root]

while children:
children_values = []
new_children = []
for c in children:
children_values.append(c.val)
if c.children:
new_children.extend(c.children)

values.append(children_values)
children = new_children

return values
```