dsa · easy

Invert Binary Tree

GreyOrangeTreeFoundation

Given the root of a binary tree (represented as a nested list where each node is [value, left, right] or None), invert the tree and return its root.

Arguments

• root — the binary tree; each node is [val, left, right] or None

**Example 1:** `` Input: [4,[2,[1,None,None],[3,None,None]],[7,[6,None,None],[9,None,None]]] Output: [4,[7,[9,None,None],[6,None,None]],[2,[3,None,None],[1,None,None]]] ``

Constraints

0 <= nodes <= 100 Hidden tests include near-max size for this bound; a slower-than-intended solution TLEs.

Examples

Example 1

Input:
[4,[2,[1,None,None],[3,None,None]],[7,[6,None,None],[9,None,None]]]

Expected:
[4,[7,[9,null,null],[6,null,null]],[2,[3,null,null],[1,null,null]]]

Example 2

Input:
None

Expected:
null

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