feat:add Solution.cpp for 0101.Symmetric Tree

Author: Stackingrule

solution/0100-0199/0101.Symmetric Tree/Solution.cpp

@@ -0,0 +1,14 @@
+class Solution {
+public:
+    bool isSymmetric(TreeNode* root) {
+    	if (!root) return true;
+    	return isSymmetric(root->left, root->right);
+    }
+
+private:
+	bool isSymmetric(TreeNode* left, TreeNode* right) {
+		if (!left && !right) return true;
+		if (!left && right || left && !right || left->val != right->val) return false;
+		return isSymmetric(left->left, right->right) && isSymmetric(left->right, right->left);
+	}
+};