Mirror Tree

Binary TreeDepth-First SearchRecursionTree

Given the root of a binary tree, transform the tree into its mirror image and return the root of the mirrored tree. A mirrored tree is a tree where the positions of the left and right children of all nodes are swapped.

Example 1

Input

[
  4,
  2,
  7,
  1,
  3,
  6,
  9
]

Output

4, 7, 2, 9, 6, 3, 1

Explanation. Swap all left and right children in the tree.

Example 2

Input

[
  1,
  2
]

Output

1, null, 2

Explanation. The node 2, originally on the left, is now on the right.

Example 3

Input

[
  1
]

Output

Explanation. A single node tree remains unchanged when mirrored.

Follow-up: Can you solve this problem both recursively and iteratively?

Constraints:

The tree will have at most 100 nodes. Each node's value is an integer.

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