ASD lab6 prob4

#include <iostream>

using namespace std;

struct nod
{
    int info;
    nod *ante, *urm;
};

struct lista
{
    nod *prim, *ultim;
};

void init(lista &c)
{
    c.prim = c.ultim = NULL;
}

void push(lista &c, nod *&start, int x)
{
    nod *p = new nod;
    p->info = x;
    p->ante = p->urm = NULL;
    if(c.prim == NULL)
    {
        c.prim = c.ultim = p;
        start->urm = p;
        p->ante = start;
        p->urm = start;
    }
    else
    {
        c.ultim->urm = p;
        p->ante = c.ultim;
        p->urm = start;
        c.ultim = p;
    }
}

void pop(lista c, nod *start, int x)
{
    nod *r = start;
    r = r->urm;
    while(r != start && x != r->info)
        r = r->urm;
    if(r != start)
    {
        r->ante->urm = r->urm;
        r->urm->ante = r->ante;
        delete r;
    }

}

void afis_lista(lista c, nod *start)
{
    nod *r = start;
    r = r->urm;
    while(r != start)
    {
        cout << r->info << ' ';
        r = r->urm;
    }
    cout << "\n";
}

int main()
{
    lista c;
    init(c);

    nod *start = new nod;
    start->urm = NULL;
    start->urm = c.prim;
    push(c, start, 3);
    push(c, start, 4);
    push(c, start, 5);
    push(c, start, 9);
    afis_lista(c, start);
    pop(c, start, 3);
    pop(c, start, 5);
    pop(c, start, 4);
    afis_lista(c, start);

    return 0;
}