Replication of complex linked list

Please implement copyRandomList function , Copy a complex list . In complex linked list , Each node has one next The pointer points to the next node , One more random The pointer points to any node in the list or null.

/*
// Definition for a Node.
class Node {
    int val;
    Node next;
    Node random;

    public Node(int val) {
        this.val = val;
        this.next = null;
        this.random = null;
    }
}
*/
/**
 Law 1： use hashMap To maintain the 
 */
class Solution {
    public Node copyRandomList(Node head) {
        if(head == null)
        return null;
        HashMap<Node,Node> hs = new HashMap<Node,Node>();
        Node curr = head;
        while(curr != null){
            hs.put(curr,new Node(curr.val));
            curr = curr.next;
        }
        curr = head;
        while(curr != null){
            hs.get(curr).next = hs.get(curr.next);
            hs.get(curr).random = hs.get(curr.random);
            curr = curr.next;
        }
        return hs.get(head);


    }
}