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 public class Solution { 2     public ListNode deleteDuplicates(ListNode head) { 3         if(head==null || head.next==null) return head; 4         ListNode safe = new ListNode(-1); 5         safe.next = head; 6         ListNode pre = safe; 7         ListNode cur = head; 8         ListNode post = head.next; 9         while(post!=null){10             if(post.val==cur.val){11                 while(post!=null && post.val==cur.val){12                     cur = post;13                     post = post.next;14                 }15                 cur = post;16                 if(post!=null)17                     post = post.next;18                 continue;19             }20              pre.next = cur;21              pre = cur;22              cur = post;23              if(post!=null)24                 post = post.next;25         }26         pre.next = cur;27         return safe.next;28     }29 }