Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.

 

 1 /**
 2  * Definition for singly-linked list.
 3  * struct ListNode {
 4  *     int val;
 5  *     ListNode *next;
 6  *     ListNode(int x) : val(x), next(NULL) {}
 7  * };
 8  */
 9 class Solution {
10 public:
11     ListNode* deleteDuplicates(ListNode* head) {
12         if(head==NULL||head->next==NULL)
13         return head;
14         ListNode *dummy=new ListNode(0);
15         dummy->next=head;
16         ListNode *p=dummy,*tmp;
17         while(p->next!=NULL)
18         {
19             if(p->next->next!=NULL)
20             {
21                 if(p->next->val==p->next->next->val)
22                 {
23                     while(p->next->val==p->next->next->val)
24                     {
25                         tmp=p->next->next->next;
26                         p->next->next=tmp;
27                         if(p->next->next==NULL)
28                         break;
29                     }
30                 tmp=p->next->next;
31                 p->next=tmp;
32                 continue;
33                 }
34             }
35             
36             p=p->next;
37             if(p==NULL)
38             break;
39             
40         }
41         return dummy->next;
42     }
43 };