#include <iostream>

using  namespace std;


struct elementas
{
    int data;
    elementas * next;
};

elementas * temp;
elementas * head;
elementas * tail;


void sukurimas(int &n);
void spausdinimas(int n);
void iterpimaspries(int &n);
void pozicija(int &n);
void pagalpozicija(int &n);
void trint(int &n);
void iterpimas(int &n);
void posk(int &n);


int main()
{
    int * p,i,n=0;
//head = NULL;
    int choice;
    bool meniu = true;
    while (meniu != false)
    {
        cout << "*******************************\n";
        cout << "1. Sukurti tiesini vienakrypti sarasa"<<endl;
        cout << "2. Atspausdinti tiesini vienakrypti sarasa"<<endl;
        cout << "3. Iterpia nauja elementa i nurodyta tiesinio saraso pozicija "<<endl;
        cout << "4. Iterpia elementa pries tam tikra sarase egzistuojanti elementa"<<endl;
        cout << "5. Istrina tiesini sarasa"<<endl;
        cout << "6. Istrina pasirinkta tiesinio saraso elementa"<<endl;
        cout << "7. UZDARYTI"<<endl;
        cout <<"Pasirinkite : "<<endl;

        cin >> choice;

        switch (choice)
        {
        case 1:
            sukurimas(n);
            break;
        case 2:
            spausdinimas(n);
            break;
        case 3:
            pozicija(n);
            break;
        case 4:
            iterpimas(n);
            break;
        case 5:
            trint(n);
            break;
        case 6:
            pagalpozicija(n);
            break;
        case 7:
            meniu = false;
            break;
        default:
            cout <<" Neegzistuoja "<<endl;
            break;
            cout << "PASIRINKITE: .\n";
            cin >> choice;
            break;
        }
    }
    return 0;
}
void sukurimas(int &n)
{
    cout <<"Keliu elementu bus vienakryptis tiesinis sarasas"<<endl;
    cin >> n;
    head = new elementas;
    cout<<"IVESKITE " <<  1 <<" ELEMENTA"<<endl;;
    cin>>head->data;
    head->next = nullptr;
    temp = head;
    tail = head;

    for(int i = 1; i< n; i++)
    {
        temp = new elementas;
        cout <<"IVESKITE "<<i + 1 <<" ELEMENTA"<<endl;
        cin>>temp->data;
        temp->next=nullptr;
        tail->next = temp;
        tail=temp;
    }
}
void spausdinimas(int n)
{

    cout << "SARASO ELEMENTAI: " << endl;
    temp = head;
    while (temp != nullptr)
    {
        cout << temp->data << endl;
        cout << "***************" << endl;
        temp = temp->next;
    }

}

void iterpimaspries(int &n)
{
    tail = new elementas;
    cout << "IVESKITE ELEMENTA: ";
    cin >> tail -> data;
    tail ->next = head;
    head = tail;
    n++;
}

void pozicija(int &n)
{
    int p;
    temp = head;
    cout << "IVESKITE POZICIJA: ";
    cin >> p;
    if (p > n || p < 1)
        cout << "NEGALIMA ITERPTI" << endl;
    else if (p == 1)
        iterpimaspries(n);
    else
    {
        tail = new elementas;
        cout << "IVESKITE ELEMENTA: ";
        cin >> tail -> data;
        for (int i = 1; i < p-1; i++)
        {
            temp = temp ->next;
        }

        tail -> next = temp -> next;
        temp -> next = tail;
        n++;
    }
}

void trint(int &n)
{
    elementas * temp2=head;
    while(head != nullptr)
    {
    temp2= head;
         head = temp2->next;
        delete temp2;
        cout<<"Istrintas "<<temp2->data<<endl;
    n--;
    }
    cout << "SARASAS ISTRINTAS" << endl;
}


void iterpimas(int &n)
{

    int p;
    cout <<"PASIRINKITE ELEMENTA:"<<endl;
    cin>>p;
    temp = head;
    for(int i = 0 ; i<n-1; i++)
    {
        if(temp->data==p)
        {
            p = i+1;//
            break;
        }
    }
    if (p > n || p < 1)
        cout << "NEGALIMA ITERPTI!" << endl;
    else if (p == 1)
        iterpimaspries(n);
    else
    {

        temp = new elementas;
        elementas * temp2=head;
        cout << "IVESKITE ELEMENTA: ";
        cin >> temp -> data;
        for (int i = 1; i < p-1; i++)
        {
            temp2= temp2 ->next;
        }

        temp -> next = temp -> next;
       // temp -> next = temp; pagal pozicija / ir iterpti pagal pozicija
        n++;
    }
}
void pagalpozicija(int &n)
{
    int sk, x = 0;
    elementas * temp2;
    cout << "IVESKITE KURI SKAICIU TRINTI: ";
    cin >> sk;

    if ( sk == head->data)
    {
        trint(n);
    }
    else
    {
        temp2 = head;
        temp = temp2 -> next;

        for (int i = 1; i <= n; i++)
        {
            if (temp -> data == sk )
            {
                delete temp;
                temp2 -> next = temp -> next;
                n--;
                x = 1;
                break;
            }
            else
            {
                cout << "NERA TOKIO SKAICIAUS" << endl;
                break;
            }

            temp = temp -> next;
            temp2 = temp2 -> next;
        }

    }
}