Binary Tree Preorder Traversal

Easy

Given the root of a binary tree, return its preorder traversal (node, left, right) as a list of values.

Example 1

Input:  root = [1,null,2,3]
Output: [1,2,3]

Example 2

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

Constraints

• 0 <= number of nodes <= 100
• -100 <= Node.val <= 100