Invert Binary Tree

Easy

Given the root of a binary tree, invert it (swap every left and right child) and return the root. Output is the inverted tree in level order.

Example 1

Input:  root = [4,2,7,1,3,6,9]
Output: [4,7,2,9,6,3,1]

Example 2

Input:  root = []
Output: []

Constraints

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