# 题目描述

Given an n-ary tree, return the preorder 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).

Recursive solution is trivial, could you do it iteratively?

Example 1:

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

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]

# 我的解法

## 解题思路

### 递归

Runtime: 60 ms, faster than 85.95% of C++ online submissions for N-ary Tree Preorder Traversal.
Memory Usage: 56.7 MB, less than 10.53% of C++ online submissions for N-ary Tree Preorder Traversal.

### 迭代

Runtime: 60 ms, faster than 85.95% of C++ online submissions for N-ary Tree Preorder Traversal.
Memory Usage: 56.5 MB, less than 10.53% of C++ online submissions for N-ary Tree Preorder Traversal.