## Question

Given the `root`

of a binary tree, *check whether it is a mirror of itself* (i.e., symmetric around its center).

**Example 1:**

Input:root = [1,2,2,3,4,4,3]Output:true

**Example 2:**

Input:root = [1,2,2,null,3,null,3]Output:false

**Constraints:**

- The number of nodes in the tree is in the range
`[1, 1000]`

. `-100 <= Node.val <= 100`

**Follow up:** Could you solve it both recursively and iteratively?

## Python Solution

def rec(ln,rn): if ln==None and rn==None: return True elif ln==None or rn==None: return False if ln.val!=rn.val: return False l = rec(ln.left,rn.right) r = rec(ln.right,rn.left) return l and r class Solution: def isSymmetric(self, root: TreeNode) -> bool: if not root: return True return rec(root.left,root.right)