Question

Given the root of a binary tree, return the preorder traversal of its nodes' values.Example 1:Input: root = [1,null,2,3]Output: [1,2,3]Example 2:Input: root = []Output: []Example 3:Input: root = [1]Output: [1]

Answer 1

Preorder traversal is a depth-first traversal method for binary trees. It visits the root node first, then recursively traverses the left subtree, and finally the right subtree. Here's an example of how you can implement it in Python:

```python

def preorderTraversal(root):

result = []

if root:

result.append(root.val)

result += preorderTraversal(root.left)

result += preorderTraversal(root.right)

return result

```

This code will return the preorder traversal of a binary tree given its root node. Is there anything else you would like to know?

Step-by-step explanation: