**Problem Statement:**
Given the required input arguments, write an efficient algorithm to solve the **Symmetric Tree** problem. Implement the required logic as specified by standard definitions for this classic algorithmic challenge.
**Hint / Expected Approach:**
Recursive mirror comparison or BFS pair check
**Edge Cases to Consider:**
- (1) Single node
- (2) All same values
- (3) Only left or only right subtrees
Examples
Example 1
Input:[1,2,2,3,4,4,3]
Output:true
Explanation: Classic symmetric
Example 2
Input:[1,2,2,null,3,null,3]
Output:false
Explanation: Asymmetric children
Example 3
Input:[]
Output:true
Explanation: Empty tree is symmetric
Constraints
▪The number of nodes in the tree is in the range [0, 2000]
▪-1000 <= Node.val <= 1000
▪Ensure depth-first or breadth-first traversals are memory-efficient