LDI

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

struct Nod
{
    int info;
    Nod *stg, *drp;
};

Nod *head, *tail;

void Init()                     /// Initializare
{
    head = tail = NULL;
}

void Creare(int x)              /// Creare l.d.i cu un nod
{
    head = new Nod;
    head -> info = x;
    head -> drp = NULL;
    head -> stg = NULL;
    tail = head;
}

void AdInceput(int x)           /// Adaugarea la inceput
{
    Nod *p;
    p = new Nod;
    p -> info = x;
    p -> drp = head;
    p -> stg = NULL;
    head -> stg = p;
    head = p;
}

void AdSfarsit(int x)           /// Adaugarea la sfarsit
{
    Nod *p;
    p = new Nod;
    p -> info = x;
    p -> stg = tail;
    p -> drp = NULL;
    tail -> drp = p;
    tail = p;
}

void AdDupaNod(Nod *p, int x)   /// Adaugarea dupa un nod
{
    Nod *q;
    q = new Nod;
    q -> info = x;
    q -> stg = p;
    q -> drp = p -> drp;
    p -> drp = q;
    p -> drp -> stg = q;
}

void ParcSD()                   /// Parcurgerea St->Dr
{
    for(Nod *p = head; p != NULL; p = p -> drp)
        cout << p -> info << " ";
    cout << "\n";
}

void ParcDS()                   /// Parcurgerea Dr->St
{
    for(Nod *p = tail; p != NULL; p = p -> stg)
        cout << p -> info << " ";
    cout << "\n";
}

Nod *Cautare(int x)             /// Cauta in lista nodul cu informatia x
{
    for(Nod *p = head; p != NULL; p = p -> drp)
        if(p -> info == x) return p;
    return NULL;
}

void StInterior(Nod *p)         /// Nodul p care este sters se afla in interiorul listei
{
    p -> stg -> drp = p -> drp;
    p -> drp -> stg = p -> stg;
    delete p;
}

void StInceput()                /// Stergerea primului nod
{
    Nod *p = head;
    p -> drp -> stg = NULL;
    head = head -> drp;
    delete p;
}

void StSfarsit()                /// Stergerea ultimului nod
{
    Nod *p = tail;
    p -> stg -> drp = NULL;
    tail = tail -> stg;
    delete p;
}

int main()
{
    int n;
    cout << "n: "; cin >> n;
    Creare(1);
    for(int i = 2; i <= n; i++)
        AdSfarsit(i);
    ParcSD();
    ParcDS();

    srand(time(0));
    int x = rand() % (n-2) + 2; cout << "\nx: " << x << "\n";
    Nod *p = Cautare(x);
    StInterior(p);
    ParcSD();
    StInceput();
    StSfarsit();
    ParcSD();


    return 0;
}