1 /*
 2  public class ListNode {
 3     int val;
 4     ListNode next = null;
 5 
 6     ListNode(int val) {
 7         this.val = val;
 8     }
 9 }
10 */
11 import java.util.HashMap;
12 public class Solution {
13     public ListNode deleteDuplication(ListNode pHead)
14     {
15         /*ListNode first = new ListNode(-1);//设置一个trick
16         first.next = pHead;
17         ListNode p = pHead;
18         ListNode last = first;
19         while(p != null && p.next != null){
20             if(p.val == p.next.val){
21                 int val = p.val;
22                 while(p!= null && p.val == val)
23                     p = p.next;
24                 last.next = p;
25             }else{
26                 last = p;
27                 p = p.next;
28             }
29         }
30         return first.next;*/
31         ListNode first = new ListNode(-1);
32         first.next = pHead;//first指向头结点，也是返回的结点
33         ListNode last = first;//使用指向p的前一个
34         ListNode p = pHead;
35         while(p != null && p.next != null){
36             if(p.val == p.next.val){
37                 int val = p.val;
38                 while(p != null && p.val == val)//删除重复的结点
39                     p = p.next;
40                 last.next = p;//指向不是重复的结点
41             }else{
42                 last = p;//指向p
43                 p = p.next;//后移一位
44             }
45         }
46         return first.next;
47     }
48 }