/*

* @lc app=leetcode id=226 lang=java

*

* [226] Invert Binary Tree

*

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

*

* algorithms

* Easy (65.55%)

* Likes: 4201

* Dislikes: 68

* Total Accepted: 605.5K

* Total Submissions: 915.9K

* Testcase Example: '[4,2,7,1,3,6,9]'

*

* 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.

*

*/

// @lc code=start

/**

* Definition for a binary tree node.

* public class TreeNode {

* int val;

* TreeNode left;

* TreeNode right;

* TreeNode() {}

* TreeNode(int val) { this.val = val; }

* TreeNode(int val, TreeNode left, TreeNode right) {

* this.val = val;

* this.left = left;

* this.right = right;

* }

* }

*/

class Solution {

public TreeNode invertTree(TreeNode root) {

if(root == null) return null;

TreeNode tmp = root.left;

root.left = invertTree(root.right);

root.right = invertTree(tmp);

return root;

}

}

// @lc code=end