Copy List with Random Pointer

 1 class Solution {
 2 public:
 3     RandomListNode *copyRandomList(RandomListNode *head) {
 4         if(head == NULL)
 5             return NULL;
 6         RandomListNode* nHead = new RandomListNode(head->label);
 7         RandomListNode* optr;
 8         RandomListNode* nptr;
 9         optr = head;
10         nptr = nHead;
11         map<RandomListNode*,RandomListNode*> m1;
12          m1[optr] = nptr;
13          nptr->random = optr->random;
14          optr = optr->next;
15         while(optr != NULL)
16         {
17            RandomListNode* tmp = new RandomListNode(optr->label);
18            nptr->next = tmp;
19            nptr = tmp;
20            nptr->random = optr->random;
21            m1[optr]=nptr;
22            optr = optr->next;
23 
24         }
25         nptr->next = NULL;
26         nptr = nHead;
27         while(nptr != NULL)
28         {
29             if(nptr->random != NULL)
30             {
31                nptr->random = m1[nptr->random];
32             }
33             nptr = nptr->next;
34         }
35         return nHead;
36     }
37 };