868. Convert Binary Tree to its Mirror

Given the root of a binary tree, transform it into its mirror image by swapping 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 mirrored tree in level order.

Examples

Input: [1,2,3,4,5]
Output: [1,3,2,null,null,5,4]
Explanation: All 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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