Lab14A

#include<iostream>
#include<iomanip>
using namespace std;

struct queue
{
    int D;
    queue* next;
    queue* prev;
};

void push(queue** top, queue** top_first_in_first_out, int element)
{
    queue* q = new queue();
    q->D = element;
    q->next = NULL;
    q->prev=NULL;
    if (*top_first_in_first_out == NULL)
    {
        *top = *top_first_in_first_out = q;
    }
    else
    {
        (*top)->next = q;
        q->prev=(*top);
        *top = q;
    }
}

void print(queue* top_first_in_first_out)
{
    queue* q = top_first_in_first_out;
    while (q != NULL)
    {
        cout << setw(10) << q->D;
        q = q->next;
    }
    cout << endl;
}


void insert_99(queue* top)
{
    //проверка если очередь пуста
     if(top==NULL){
         cout<<"queue is empty!";
         exit(1);
     }

    //проверка! если у нас в очереди один улемент то заканчиваем программу//так как некорруктный ввод данных для вставки
    if(top->next==NULL && top->prev==NULL){
        cout<<"в очереди один улемент!!!";
        exit(1);
    }

    // -4   -5 -6 8        4 -5  -6
    //    99
    while (top->next != NULL)
    {
        if(top->D<0 && top->next->D<0){
            queue *q=new queue();
            q->D=99;
            q->next=top->next;
            q->prev=top;

            top->next->prev=q;
            top->next=q;

            top=top->next;
        }
        top=top->next;
    }
}


void delete_queue(queue* top_first_in_first_out)
{
    queue* q ;

    while (top_first_in_first_out != NULL)
    {
        q = top_first_in_first_out;
        top_first_in_first_out = top_first_in_first_out->next;
        q->next = NULL;
        delete q;
    }
}

int main()
{
    queue* top = NULL;
    queue* top_first_in_first_out = NULL;

    int n;
    cout << "Write number of elements: " << endl;
    cin >> n;
    int element=0;

    for(int i=0;i<n;i++){
        cin>>element;
        push(&top, &top_first_in_first_out, element);
    }



    cout << endl<<endl<< "Old queue:" << endl;
    print(top_first_in_first_out);

    insert_99(top_first_in_first_out);

    cout << endl << "New queue" << endl;
    print(top_first_in_first_out);

    delete_queue(top_first_in_first_out);
}