Problem LeetCode 226 - Invert Binary Tree
Easy
Given the root of a binary tree, invert the tree, and return its root.
Input: root = [4,2,7,1,3,6,9] Output: [4,7,2,9,6,3,1]
Input: root = [2,1,3] Output: [2,3,1]
Input: root = [] Output: []
- The number of nodes in the tree is in the range [0, 100].
- -100 <= Node.val <= 100