1 struct Node{2     vector<Node*> neighbors;3 };

 1 typedef unordered_map<Node*, Node*> Map; 2  3 Node* cloneGraph(Node* graph) 4 { 5     if (!graph) 6         return NULL; 7  8     Map map; 9     Node* graphCopy = new Node();10     map[graph] = graphCopy;11 12     queue<Node*> q;13     q.push(graph);14     while (!q.empty()) {15         Node* node = q.front();16         q.pop();17         int n = node->neighbors.size();18         for (int i = 0; i < n; i++) {19             Node* neighbor = node->neighbors[i];20             if (map.find(neighbor) == map.end()) {21                 Node* copy = new Node();22                 map[neighbor] = copy;23                 map[node]->neighbors.push_back(copy);24                 q.push(neighbor);25             } else {26                 map[node]->neighbors.push_back(map[neighbor]);27             }28         }29         return graphCopy;30 }