SDiZO, lab2c (lista jednokierunkowa)

gistfile1.c

#include <iostream>
#include <time.h>
using namespace std;

struct list_el
{
    int key;
    list_el *next;
};

int add(list_el *&head, int value)
{
    if(head == NULL){
        head = new list_el;
        head->key = value;
        head->next = NULL;
        return 1;
    }
        
    if(value < head->key){
        list_el *tmp = head;
        head = new list_el;
        head->key = value;
        head->next = tmp;
        return 1;
    }
        
    if(value == head->key)
        return 0;
        
    list_el *curr = head;
    
    while(curr->next && curr->next->key < value)
        curr = curr->next;
    
    if(curr->next == NULL){
        curr->next = new list_el;
        curr->next->key = value;
        curr->next->next = NULL;
        return 1;
    } else {
        if(value == curr->next->key)
                return 0;
        
        list_el* tmp = curr->next;
        curr->next = new list_el;
        curr->next->key = value;
        curr->next->next = tmp;
        return 1;
    }
}

void randomElements(list_el *&head)
{
    int size;
    cout << "Ile elementow wylosowac? ";
    cin >> size;
    for(int i = 0; i < size; ){
        if(add(head, rand() % 20)) 
            i++;
    }
}

void printAll(list_el *head)
{
    if(!head){
        cout << "Lista pusta\n";
        return;
    }
    list_el *curr = head;
    while(curr){
        cout << curr->key << " ";
        curr = curr->next;
    }
    cout << endl;
}

int searchElement(list_el *head)
{
    int value, x = 0;
    cout << "Podaj wartosc: ";
    cin >> value;
    while(head){
        if(head->key == value){
            cout << "Szukana wartosc to: " << head->key << endl;
            return head->key;
        } else {
            x = 1;
        }
        head = head->next;    
    }
    if(x) cout << "Brak wskazanego elementu\n";
}

void deleteElement(list_el *&head, int value)
{
    if(!head){
         cout << "Lista pusta\n";
         return;
    }
    
    if(head->key == value){
        list_el *tmp = head;
        head = head->next;
        delete tmp;
        return;
    }
    
    list_el *curr = head;
    while(curr){
        if(curr->next->key == value){
            list_el *tmp = curr->next;
            curr->next = curr->next->next;
            delete tmp;
            return;
        }
        curr = curr->next;
    }    
}

int main()
{
    srand((unsigned int)time(NULL));
    list_el *lista = NULL;
    int i, k, value;
    
    while(k){
        cout << "1. Dodaj losowe\n2. Dodaj element\n3. Znajdz elment\n4. Usun element\n5. Pokaz wszystko\n6. Wyjdz\n";
        cin >> i;
        switch(i){
            case 1: randomElements(lista); break;
            case 2: cout << "Podaj wartosc: "; cin >> value; add(lista, value); break;
            case 3: searchElement(lista); break;
            case 4: cout << "Podaj wartosc: "; cin >> value; deleteElement(lista, value); break;
            case 5: printAll(lista); break;
            case 6: k = 0; break;
            default: cout << "Zly wybor\n"; break;
        }
    }
}