/**
 * Definition for ListNode
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */

public class Solution {
    /**
     * @param head: head is the head of the linked list
     * @return
 
: head of linked list
     */
       public ListNode deleteDuplicates(ListNode head) {
            if(head==null||head.next==null){
                   return head;
               }
            ListNode p=head;
            while(p.next!=null){
            if(p.val!=p.next.val){
                p
 
=p.next;
                }
            else {
                p.next=p.next.next;
                }
            }
            return head;
         }
    }

LintCode 112---刪除排序鏈表中的重復元素