删除链表中重复的结点

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
        val(x), next(NULL) {
    }
};
*/
class Solution {
public:
    ListNode* deleteDuplication(ListNode* pHead)
    {
        if (pHead == NULL || pHead->next == NULL)
            return pHead;

        /*---------先为链表创建一个头结点---------*/

        int firstNumber = pHead->val;

        //假设我的头结点数值为-1
        int myFirst = -1;

        //万一链表的头结点也为-1，那么我就改成-2
        if (myFirst == firstNumber)
        {

            myFirst = -2;
        }
        ListNode *head = new ListNode(myFirst);
        head->next = NULL;
        head->next = pHead;

        ListNode *p = head;
        ListNode *q = head->next;

        while (q)
        {
            while (q->next && (q->next->val == q->val))
            {
                q = q->next;
            }
            if (p->next != q)
            {

                q = q->next;
                p->next = q;
            }
            else
            {
                p = q;
                q = q->next;
            }
        }

        //返回的时候，注意去掉头结点（自己创建的辅助节点）
        return head->next;

    }
};