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.

本欲援笔立就, 奈何两次夭折

其一, 略else

其二, while(p&&p->next)略p

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