# Invert binary tree

A problem that Homebrew's author complained.

Invert a binary tree. Problem from leetcode.

Here's the input:

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

and the out put looks like:

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

This problem was inspired by this tweet.

Here's the solution implemented in Java.

``````/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
class Solution {
public TreeNode invertTree(TreeNode root) {
if(null != root){
TreeNode leftChild = root.left;
root.left = root.right;
root.right = leftChild;
root.left = invertTree(root.left);
root.right = invertTree(root.right);
}
return root;
}
}
``````

There's much different logic behind software engineering with computer science. Max replied this question about it on quora.com after 2 years.

#### Replies

Search this URL on mastodon to reply:
https://lawrenceli.me/blog/invert-binary-tree  Scan the QR Code to leave a tip :)
Privacy· Status· 2023 ©️ Lawrence Li