RemoveDuplicatesfromSortedList

/Remove Duplicates from Sorted List My Submissions Question Solution 
//Total Accepted: 74313 Total Submissions: 214827 Difficulty: Easy
//Given a sorted linked list, delete all duplicates such that each element appear only once.
//
//For example,
//Given 1->1->2, return 1->2.
//Given 1->1->2->3->3, return 1->2->3.
public class RemoveDuplicatesfromSortedList {


public static void main(String[] args) {
// TODO Auto-generated method stub


}
public ListNode deleteDuplicates(ListNode head) {
  ListNode prehead=new ListNode(0);
  ListNode p=head;
  ListNode q=prehead;
  while(p!=null){
  if(q==prehead){
  q.next=p;
  q=q.next;
  }else{
  if(q.val!=p.val){
  q.next=p;
  q=q.next;
  }
  }
  p=p.next;
  }
  //最后的处理，q后面为空
  q.next=null;
  return prehead.next;
    }


}