Coding Trainer
Invert Binary Tree
Problem
Invert Binary Tree
Given the root of a binary tree, invert the tree (mirror it left-to-right at every node), and return its root.
Example 1:
Input: root = [4,2,7,1,3,6,9]
Output: [4,7,2,9,6,3,1]
Example 2:
Input: root = [2,1,3]
Output: [2,3,1]
Example 3:
Input: root = []
Output: []
Constraints:
- The number of nodes is in the range [0, 100]
- -100 ≤ Node.val ≤ 100