Given the root of a binary tree represented as a level-order array (with `null` for missing nodes), invert the tree and return the inverted tree as a level-order array.
Inverting a binary tree means swapping every left node with its corresponding right node.
For example, `[4, 2, 7, 1, 3, 6, 9]` represents:
```
4
/ \
2 7
/ \ / \
1 3 6 9
```
After inverting:
```
4
/ \
7 2
/ \ / \
9 6 3 1
```
Return `[4, 7, 2, 9, 6, 3, 1]`.
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:[]
Constraints
- The number of nodes in the tree is in the range [0, 100].
- -100 <= Node.val <= 100