Given the root of a binary tree, invert the tree and return the root of the inverted tree. Pattern focus: Preorder DFS (Root First). Visit the node first, then swap its children and continue recursively.
root = binary tree root
level-order array representation of the inverted tree
Example 1:
Input:
root = [4,2,7,1,3,6,9]
Output:
[4,7,2,9,6,3,1]
Explanation:
Every left child becomes a right child and vice versa.
Example 2:
Input:
root = [2,1,3]
Output:
[2,3,1]
Explanation:
The children of the root are swapped.