struct ListNode* mergeNodes(struct ListNode* head){
    struct ListNode* slow = head;
    struct ListNode* fast = head->next;
    while(fast)
    {
        if(fast->val == 0 && fast->next != NULL)
        {
            slow->next = fast;
            slow = slow->next;
        }
        slow->val += fast->val;
        fast = fast->next;
    }
    //删除末尾的0
    slow->next = NULL;
    return head;
}