remove-duplicates-from-sorted-list （删除）

#include<iostream>
#include<cstdio>
using namespace std;
struct ListNode {
     int val;
     ListNode *next;
     ListNode(int x) : val(x), next(NULL) {}
 };
class Solution {
public:
    ListNode *deleteDuplicates(ListNode *head) {
        ListNode *pre = new ListNode(666);
        pre->next = head;
        ListNode *p = pre, *q;
        while (p->next&&p->next->next){
            if (p->next->val == p->next->next->val){
                q = p->next->next->next;
                while (q&&q->val == p->next->val)q = q->next;
                p->next->next = q;
            }
            else{
                p = p->next;
            }
        }
        return pre->next;
    }
};