846. Check if Binary Tree is Symmetric

Given the root of a binary tree, determine whether it is symmetric (a mirror image of itself around its center). Return true or false. The tree is given as a level-order array with null for missing children.

Input: A level-order array of the tree.

Output: Boolean — true or false.

Examples

Input: [1,2,2,3,4,4,3]
Output: true
Explanation: The tree mirrors itself.

Input: [1,2,2,null,3,null,3]
Output: false
Explanation: Not a mirror image.

Input: [1]
Output: true
Explanation: Single node is symmetric.

Constraints

• 0<=nodes<=10^4
• -1000<=value<=1000

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