T3

#include <bits/stdc++.h>

using namespace std;

struct Nod {
    int val;
    Nod *next = NULL;
};

struct Lista {
    Nod *prim = NULL, *ult = NULL, *p = NULL;
    /// int lg = 0;

    void AdaugareInceput(int x) {
        /// if(lg == 0) {
        if(prim == NULL) {
            prim = new Nod;
            prim->val = x;
            prim->next = NULL;
            ult = prim;
        }
        else {
            p = new Nod;
            p->val = x;
            p->next = prim;
            prim = p;
        }
        /// lg++;
    }

    void AdaugareSfarsit(int x) {
        /// if(lg == 0) {
        if(ult == NULL) {
            ult = new Nod;
            ult->val = x;
            ult->next = NULL;
            prim = ult;
        }
        else {
            p = new Nod;
            p->val = x;
            p->next = NULL;
            ult->next = p;
            ult = p;
        }
        /// lg++;
    }

    void Afisare() {
        cout << "\n";

        p = prim;
        while(p != NULL) {
            cout << p->val << " ";
            p = p->next;
        }

        cout << "\n";
    }

    int CautareDupaValoare(int v) {
        int poz = 1;

        p = prim;
        while(p != NULL) {
            if(p->val == v) return poz;
            p = p->next;
            poz++;
        }

        return -1;
    }

    int CautareDupaPozitie(int poz) {
        if(poz < 1) return -1;
        int poz2 = 1;

        p = prim;
        while(p != NULL) {
            if(poz == poz2) return p->val;
            p = p->next;
            poz2++;
        }

        return -1;
    }

    void AdaugareDupaValoare(int v, int x) {
        p = prim;
        while(p != NULL) {
            if(p->val == v) {
                Nod *aux = new Nod;
                aux->val = x;
                aux->next = p->next;

                p->next = aux;

                if(p == ult) ult = aux;

                return;
            }
            p = p->next;
        }
    }

    void AdaugareDupaPozitie(int poz, int x) {
        if(poz < 1) return;

        int poz2 = 1;

        p = prim;
        while(p != NULL) {
            if(poz == poz2) {
                Nod *aux = new Nod;
                aux->val = x;
                aux->next = p->next;

                p->next = aux;

                if(p == ult) ult = aux;

                return;
            }
            p = p->next;
            poz2++;
        }
    }

    void StergereDupaValoare(int v) {
        Nod *prev;

        p = prev = prim;
        while(p != NULL) {
            if(p->val == v) {
                if(p == prim && p == ult) {
                    prim = ult = p->next; /// NULL
                    delete p;
                    return;
                }
                if(p == prim) {
                    prim = p->next;
                    delete p;
                    return;
                }
                if(p == ult) {
                    ult = prev;
                    delete p;
                    return;
                }

                prev->next = p->next;
                delete p;
            }
            prev = p;
            p = p->next;
        }
    }

    void StergereDupaPozitie(int poz) {
        if(poz < 1) return;

        Nod *prev;
        int poz2 = 1;

        p = prev = prim;
        while(p != NULL) {
            if(poz == poz2) {
                if(p == prim && p == ult) {
                    prim = ult = p->next; /// NULL
                    delete p;
                    return;
                }
                if(p == prim) {
                    prim = p->next;
                    delete p;
                    return;
                }
                if(p == ult) {
                    ult = prev;
                    ult->next = NULL;
                    delete p;
                    return;
                }

                prev->next = p->next;
                delete p;
            }
            poz2++;
            prev = p;
            p = p->next;
        }
    }

};

int main() {
    Lista L;

    int rasp = 1, v, p, x;
    while(rasp) {
        cout << "1) Adauga un element la inceputul listei.\n";
        cout << "2) Adauga un element la finalul listei.\n";
        cout << "3) Afiseaza lista.\n";
        cout << "4) Cauta un element dupa o valoare.\n";
        cout << "5) Cauta un element dupa o pozitie.\n";
        cout << "6) Insereaza un element dupa o valoare.\n";
        cout << "7) Insereaza un element dupa o pozitie.\n";
        cout << "8) Sterge un element dupa o valoare.\n";
        cout << "9) Sterge un element dupa o pozitie.\n";
        cout << "0) Iesire\n";
        cout << "\n";

        cout << "Raspuns: "; cin >> rasp;

        switch(rasp) {
            case 1:
                cout << "Element: "; cin >> x;
                L.AdaugareInceput(x);
                break;
            case 2:
                cout << "Element: "; cin >> x;
                L.AdaugareSfarsit(x);
                break;
            case 3:
                cout << "Elementele: ";
                L.Afisare();
                break;
            case 4:
                cout << "Valoare: "; cin >> v;
                cout << "Pozitia " << L.CautareDupaValoare(v) << "\n";
                break;
            case 5:
                cout << "Pozitie: "; cin >> p;
                cout << "Valoarea " << L.CautareDupaPozitie(p) << "\n";
                break;
            case 6:
                cout << "Valoare: "; cin >> v;
                cout << "Element: "; cin >> x;
                L.AdaugareDupaValoare(v, x);
                break;
            case 7:
                cout << "Pozitie: "; cin >> p;
                cout << "Element: "; cin >> x;
                L.AdaugareDupaPozitie(p, x);
                break;
            case 8:
                cout << "Valoare: "; cin >> v;
                L.StergereDupaValoare(v);
                break;
            case 9:
                cout << "Pozitie: "; cin >> p;
                L.StergereDupaPozitie(p);
                break;
            default:
                break;
        }

        cout << "\n";
    }


    return 0;
}