Add cycle detect adding edges

Network.h

@@ -8,6 +8,8 @@ namespace bayesnet {
     private:
         map<string, Node*> nodes;
         map<string, torch::Tensor> cpds;  // Map from CPD key to CPD tensor
+        Node* root = nullptr;
+        bool isCyclic(const std::string&, std::unordered_set<std::string>&, std::unordered_set<std::string>&);
     public:
         ~Network();
         void addNode(string, int);
@@ -16,6 +18,8 @@ namespace bayesnet {
         void fit(const vector<vector<int>>&, const int);
         torch::Tensor& getCPD(const string&);
         void setCPD(const string&, const torch::Tensor&);
+        void setRoot(string);
+        Node* getRoot();
     };
 }
 #endif