18_2

struct Node
{
    int x;
    Node* next;
};

Node* pop_back(Node* &head, Node* &tail)
{
    Node* current = head;
    while (current->next != tail)
        current = current->next;
    Node* tmp = tail;
    tail = current;
    return tmp;
}

int main(char fileName[244])
{
    Node* head;
    Node* tail;
    head = nullptr;
    tail = nullptr;
    printf("Введите количество элементов очереди\n");
    int n,x;
    while (!scanf("%d", &n) || n<=0)
    {
        rewind(stdin);
    }
    Node*current = nullptr;
    int xpre;
    for (int i = 0; i < n; i++)
    {
        printf("Введите элемент очереди\n");
        if (i == 0)
            while (!scanf("%d", &x)) rewind(stdin);
        else while (!scanf("%d", &x) || x < xpre) rewind(stdin);
        xpre = x;
        if (head == nullptr)
        {
            head = (Node*)malloc(sizeof(Node));
            head->x = x;
            head->next = nullptr;
            current = head;
        }
        else
        {
            current->next = (Node*)malloc(sizeof(Node));
            current = current->next;
            current->x = x;
            current->next = nullptr;
        }
    }
    FILE*f = fopen(fileName, "wb");
    Node* c;
    while (head != tail)
    {
        c = pop_back(head, tail);
        fwrite(c, sizeof(Node), 1, f);
    }
}