Solution (leetcode-in-java 1.21 API)

java.lang.Object
- g0501_0600.s0589_n_ary_tree_preorder_traversal.Solution

```
public class Solution
extends Object
```
589 - N-ary Tree Preorder Traversal.
Easy

Given the root of 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)

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 number of nodes in the tree is in the range [0, 10⁴].
- 0 <= Node.val <= 10⁴
- The height of the n-ary tree is less than or equal to 1000.
Follow up: Recursive solution is trivial, could you do it iteratively?

- Constructor Summary
  
  Constructors
  Constructor Description
  
  Solution()
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  List<Integer> preorder(Node root)
  - Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- Solution
```
public Solution()
```

Method Detail

preorder

public List<Integer> preorder(Node root)