Description
Given the root of a binary tree, check whether it is a mirror of itself (i.e., symmetric around its center).
Examples
Input:
root = [1,2,2,3,4,4,3]Output:
trueExplanation:
The tree is symmetric around its center.
Input:
root = [1,2,2,null,3,null,3]Output:
falseExplanation:
The tree is not symmetric.
Input:
root = [1]Output:
trueExplanation:
A single-node tree is symmetric.
Constraints
- •
The number of nodes in the tree is in the range [1, 1000] - •
-100 ≤ Node.val ≤ 100