struct ListNode* removeElements(struct ListNode* head, int val) 
{
    struct ListNode* prv = NULL;
    struct ListNode* cur = head;

    // 处理头节点等于val的情况
    while (cur != NULL && cur->val == val) 
    {
        head = cur->next;
        free(cur);
        cur = head;
    }

    // 处理中间节点和尾节点等于val的情况
    while (cur != NULL) 
    {
        if (cur->val == val) 
        {
            prv->next = cur->next;
            free(cur);
            cur = prv->next;
        }
        else 
        {
            prv = cur;
            cur = cur->next;
        }
    }

    return head;
}