Remove Linked List Elements（移除列表中指定的元素）

Remove all elements from a linked list of integers that have value val.

Example
Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6
Return: 1 --> 2 --> 3 --> 4 --> 5

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution 
{
public:
    ListNode* removeElements(ListNode* head, int val) 
    {
        /*ListNode *myhead=new ListNode(0);
        ListNode *q=myhead;
        while(head)
        {
            if(head->val!=val)
            {
                ListNode* p=new ListNode(head->val);
                q->next=p;
                q=q->next;
            }
            head=head->next;
        }
        return myhead->next;*/
        
        ListNode **p = &head;
        while (*p != NULL)
        {
            if ((*p)->val == val)
                *p = (*p)->next;
            else
                p = &(*p)->next;
        }
        
        return head;
    }
};