LeetCode--No.83--Remove Duplicates From Sorted List

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.

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */public class Solution {    public ListNode deleteDuplicates(ListNode head) {        ListNode p = head;        if (head == null || head.next == null)            return head;        while(p != null && p.next != null){            if (p.next.val == p.val){                if (p.next.next == null)                    p.next = null;                else                    p.next = p.next.next;            }            else                p = p.next;        }        return head;    }}