Copy List with Random Pointer

1. Title

2. Http address

https://leetcode.com/problems/copy-list-with-random-pointer/

3. The question

A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.

Return a deep copy of the list.

4. My code(AC)

 1 class RandomListNode {
 2     int label;
 3     RandomListNode next,random;
 4     public RandomListNode(int x)
 5     {
 6             this.label = x;
 7     }
 8 
 9 }
10 
11 //Accpeted
12     public static RandomListNode copyRandomList(RandomListNode head)
13     {
14             Map<RandomListNode,RandomListNode> mapH = new HashMap<RandomListNode,RandomListNode>();
15             RandomListNode re,    q,end;
16             RandomListNode p = head;
17             re = null;
18             end = null;
19             while( p != null )
20             {
21                 q = new RandomListNode(p.label);
22                 if( end == null)
23                 {
24                     re = q;
25                     end = q;
26                 }else{
27                     end.next = q;
28                     end = q;
29                 }
30                 mapH.put(p,q);
31                 p = p.next;
32             }
33 
34             p = head;
35             q = re;
36             while( p != null && q != null) {
37                 if( p.random != null )
38                 {
39                     q.random = mapH.get(p.random);
40                 
41                 }else{
42                     q.random = null;
43                 }
44                 p = p.next;
45                 q = q.next;
46             }
47         return re;
48 
49     }