/* https://leetcode.com/problems/invert-binary-tree/#/description
Invert a binary tree.

     4
   /   \
  2     7
 / \   / \
1   3 6   9
to
     4
   /   \
  7     2
 / \   / \
9   6 3   1
Trivia:
This problem was inspired by this original tweet by Max Howell:
Google: 90% of our engineers use the software you wrote (Homebrew), but you can't invert a binary tree on a whiteboard so fuck off.
*/

package ltree

func invertTree(root *TreeNode) *TreeNode {
	if root != nil {
		root.Left, root.Right = invertTree(root.Right), invertTree(root.Left)
	}
	return root
}
