/** * 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;         }    }