Given the root of a binary tree
root, check whether the tree is mirror-symmetric about its center.Example 1
Input: root = [1,2,2,3,4,4,3]
Output: true
Explanation: The left and right subtrees are mirror images.
Output: true
Explanation: The left and right subtrees are mirror images.
Example 2
Input: root = [1,2,2,null,3,null,3]
Output: false
Explanation: The subtrees are not mirror images.
Output: false
Explanation: The subtrees are not mirror images.