# Symmetric Tree Problem & Solution

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

## C++ Solution

``````#pragma GCC optimize("Ofast")
#pragma GCC optimization("max-inline-insns-recursive-auto")

static const int _=[](){std::ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

/**
* struct TreeNode {
*   int val;
*   TreeNode *left;
*   TreeNode *right;
*   TreeNode() : val(0), left(nullptr), right(nullptr) {}
*   TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
*   TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
bool isSymmetric(TreeNode* root) {
if (root == nullptr) {
return true;
}

return isSymmetric(root->left, root->right);
}

private:
bool isSymmetric(TreeNode* left, TreeNode* right) {
if ((left != nullptr && right == nullptr) ||
(left == nullptr && right != nullptr)) {
return false;
}

if (left == nullptr && right == nullptr) {
return true;
}

return left->val == right->val &&
isSymmetric(left->left, right->right) &&
isSymmetric(left->right, right->left);
}
};
``````