LeetCode 429 N-ary Tree Level Order Traversal 解题报告

题目要求

Given an n-ary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).

题目分析及思路

给定一棵N叉树，要求返回它的层次遍历结果。可以使用collections.deque来保存结点，按照每一层的长度来遍历结点。

python代码

"""

# Definition for a Node.

class Node:

    def __init__(self, val, children):

        self.val = val

        self.children = children

"""

class Solution:

    def levelOrder(self, root: 'Node') -> List[List[int]]:

        order1 = []

        q = collections.deque()

        q.append(root)

        while q:

            order2 = []

            size = len(q)

            for _ in range(size):

                node = q.popleft()

                if not node:

                    continue

                order2.append(node.val)

                for child in node.children:

                    q.append(child)

            if order2:

                order1.append(order2)

        return order1