Invert Binary Tree

Input: root = [4,2,7,1,3,6,9]

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

The tree is inverted by swapping left and right children at every level. Node 4's children swap (2↔7), then node 7's children swap (6↔9) and node 2's children swap (1↔3).

Input: root = [2,1,3]

Output: [2,3,1]

The root's left child (1) and right child (3) are swapped.

Input: root = []

Output: []

An empty tree remains empty after inversion.

Invert Binary Tree

Problem

Constraints

Examples