# Question

Formatted question description: https://leetcode.ca/all/226.html

 226	Invert Binary Tree

Invert a binary tree.

Example:

Input:

4
/   \
2     7
/ \   / \
1   3 6   9

Output:

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 f*** off.

@tag-tree


# Algorithm

Exchange the current left and right nodes, and call recursion directly.

Java