845. Mirror / Invert a Binary Tree

Given the root of a binary tree, invert it (swap the left and right children of every node) and return the resulting tree as a level-order array with null for missing children.

Input: A level-order array of the tree.

Output: Array — the inverted tree in level order.

Examples

Input: [4,2,7,1,3,6,9]
Output: [4,7,2,9,6,3,1]
Explanation: All left/right children swapped.

Input: [1]
Output: [1]
Explanation: Single node unchanged.

Input: []
Output: []
Explanation: Empty tree.

Constraints

• 0<=nodes<=10^4
• -1000<=value<=1000

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