class Solution {
public:
    map<Node*,Node*> st;
    Node *cloneGraph(Node *node){
        Node* ret = new Node(node->val,vector<Node*>());
        st[node]=ret;
        for(auto x:node->neighbors){
            auto p = st.find(x);
            if(p==st.end()){
                ret->neighbors.push_back(cloneGraph(x));
            }else ret->neighbors.push_back(p->second);
        }
        return ret;
    }
};
/*
// Definition for a Node.
class Node {
public:
    int val;
    vector<Node*> neighbors;

    Node() {}

    Node(int _val, vector<Node*> _neighbors) {
        val = _val;
        neighbors = _neighbors;
    }
};
*/