Invert Binary Tree

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

Given the root of a binary tree, invert the tree, 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: []

Solution:

Continue talking about the binary trees. We have to swap left and right elements. We can do it in the post-order traversal. Iterate till the leaf node, swap left and right, and return the node.

  public TreeNode invertTree(TreeNode root) {
     
    if(root == null){
      return null;
    }
     
    TreeNode left = invertTree(root.left);
    TreeNode right = invertTree(root.right);
     
    root.left = right;
    root.right = left;
    return root;
  }