101. Symmetric Tree

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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

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solution.cppC++17

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