/*
// Definition for a Node.
class Node {
public:
    int val;
    vector<Node*> neighbors;
    
    Node() {
        val = 0;
        neighbors = vector<Node*>();
    }
    
    Node(int _val) {
        val = _val;
        neighbors = vector<Node*>();
    }
    
    Node(int _val, vector<Node*> _neighbors) {
        val = _val;
        neighbors = _neighbors;
    }
};
*/

class Solution {
public:
    unordered_map<Node*,Node*> map;
    
    Node* cloneGraph(Node* node) {
        if (node == NULL){
            return NULL;
        }
        else{
            if (map.find(node) != map.end()){
                return map[node];
            }
            
            Node* clone = new Node(node->val);
            map[node] = clone;
            
            for (Node* i:node->neighbors){
                clone->neighbors.push_back(cloneGraph(i));
            }
            
            return clone;
        }
    }
};