Copy Linked List with random pointer

/* // 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; } } */ class Solution { public Node copyRandomList(Node head) { HashMap<Node,Node> map = new HashMap<>(); Node node = new Node(0); Node temp = node; while(head!=null){ Node duplicateNode = get(map,head); temp.next = duplicateNode; Node duplicateRandomNode = get(map, head.random); duplicateNode.random = duplicateRandomNode; temp = temp.next; head = head.next; } return node.next; } public Node get(Map<Node,Node> map, Node node){ if(node ==null) return null; if(map.containsKey(node)) return map.get(node); map.put(node, new Node(node.val)); return map.get(node); } } 

/* // 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; } } */ class Solution { public Node copyRandomList(Node head) { Map<Node,Node> map = new HashMap<>(); return copy(head,map); } public Node copy(Node node,Map<Node,Node> map){ if(node == null) return null; if(map.containsKey(node)) return map.get(node); map.put(node, new Node(node.val)); Node duplicate = map.get(node); duplicate.next = copy(node.next,map); duplicate.random = copy(node.random,map); return duplicate; } }