1 class Solution {
2 public:
3 ListNode* deleteDuplicates(ListNode* head) {
4 if(head == NULL) return head;
5 ListNode* res = new ListNode(0);
6 res->next = head;
7
8 ListNode* prev = res;
9
10 while(head && head->next){
11 if(head->val == head->next->val){
12 while(head->next && head->val == head->next->val){
13 ListNode* tmp = head->next;
14 head->next = head->next->next;
15 delete tmp;
16 }
17 ListNode* tmp = head;
18 prev->next = head->next;
19 head = head->next;
20 delete tmp;
21 }
22 else{
23 prev = head;
24 head = head->next;
25 }
26 }
27 return res->next;
28 }
29 };
