Remove Linked List Elements

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 node(-1);
        node.next=head;
        ListNode *pre=&node;
        while(head!=NULL)
        {
            if(head->val==val)
            {
                pre->next=head->next;
                delete head;
                head=pre->next;
            }
            else
            {
                pre=pre->next;
                head=head->next;
            }

        }
        return node.next;
    }
};