leetcode--011 copy list with random pointer

 1 package leetcode;
 2 
 3 class RandomListNode {
 4     int label;
 5     RandomListNode next, random;
 6 
 7     public RandomListNode(int x) {
 8         this.label = x;
 9     }
10 }
11 
12 public class CopyListRandom {
13     public RandomListNode copyRandomList(RandomListNode head) {
14         if(head==null)return head;
15         RandomListNode po= head.next;
16         RandomListNode p=head;
17         while(p!=null){
18             RandomListNode newnode=new RandomListNode(p.label);
19             po=p.next;
20             newnode.next=p.next;
21             p.next=newnode;
22 
23             p=po;            
24         }
25         p=head;
26         while(p!=null){
27             if(p.random!=null){
28             p.next.random=p.random.next;
29         }
30             p=p.next.next;
31         }
32         p=head;
33         RandomListNode h=head.next;
34         RandomListNode q=h;
35         while(q!=null){
36             p.next=q.next;
37             p=q;
38             q=q.next;            
39         }
40         return h;
41     }
42 }