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

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) {}
 * };
 */ // 6,2,6,1,2,6
class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        ListNode **list = &head;
        ListNode *temp = NULL;
       
        while (*list)
        {
            if ((*list)->val == val)
            {
                temp = (*list);
                (*list) = (*list)->next;
                free(temp);
            }
            else
            {
                list = &(*list)->next;
            }
        }

    return head;
    }
};