[leetcode] 429. N-ary Tree Level Order Traversal

[leetcode] 429. N-ary Tree Level Order Traversal

Description

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 1000The total number of nodes is between [0, 10^4]

分析

题目的意思是：实现一个n叉树的层序遍历。跟二叉树差不多，用层序遍历就行了。

代码

"""# 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 [] q=collections.deque() q.append(root) res=[] while(q): n=len(q) ans=[] for i in range(n): node=q.popleft() ans.append(node.val) for child in node.children: q.append(child) res.append(ans) return res

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