/******************************************************** 
  Author: Denis Biondic @ ETF Bihac
  Date: 16.02.07 20:49
  Description: Simple linked list with:
                  - insertFirst()
                  - deleteFirst()
                  - deleteLink()
                  - deleteDivisibleByFour()
                  - find()
                  - showList()

*********************************************************/


#include <iostream>
using namespace std;

//======================================================//
//====================== Link ==========================//
//======================================================//


class Link
{
    public:
 Link *next;
 int data;
 
 Link( int );
};

//=================== konstruktor =======================//

Link::Link(int d)
 {
  next = NULL;
  data = d;      
 }


//======================================================//
//=================  SingleLinkedList ==================//
//======================================================//


class SingleLinkedList
{
 Link *first;
 
    public:
 SingleLinkedList();
 ~SingleLinkedList();
 
 void insertFirst(int elem);
 
 void deleteFirst(); 
 void deleteLink(int index);
 void deleteDivisibleByFour();
 
 int find(int num);
 void showList();
};

//=================== konstruktor =======================//

SingleLinkedList::SingleLinkedList()
 {
  first = NULL;                                   
 }

//=================== destruktor ========================//

SingleLinkedList::~SingleLinkedList()
 {
  Link *current = first;
  Link *toDelete;
  
  while (current != NULL)                                   
   {
    toDelete = current;
    current = current->next;
    delete toDelete;
   }
 }

//==================== insertFirst() ====================//

void SingleLinkedList::insertFirst(int elem)
 {
  Link *newLink = new Link(elem);
  
  if (first == NULL)
   {
    first = newLink;
   }
  else
   {
    newLink->next = first;
    first = newLink;
   }  
 }

//==================== deleteFirst() ====================//

void SingleLinkedList::deleteFirst()
 {
  Link *toDelete = first;
  
  first = first->next;
  
  delete toDelete;
 }

//======================  deleteLink() ==================//

void SingleLinkedList::deleteLink(int index)
 {
  if (index == 0)
   this->deleteFirst();
  else
   {
    Link *current = first;
    
    for (int i=0; i < index-1; i++)
     current = current->next;
    
    Link *toDelete = current->next;
    current->next = current->next->next;
    delete toDelete; 
   }
 }

//===================  deleteByFour()  ==================//

void SingleLinkedList::deleteDivisibleByFour()
 {
  Link *current = first;
  int index = 0;
  
  while (current != NULL)
   {
    if ((current->data % 4 ) == 0)
     {
      current = current->next;
      this->deleteLink(index);
     }
    else
     {
      current = current->next;
      index++;
     }
   }    
 }

//======================= find() ========================//

int SingleLinkedList::find(int num)
 {
  Link *current = first;
  int index = 0;
  
  while (current->data != num)
   {     
    index++;
    current = current->next;
    if (current == NULL)
     return -1;
   }
  return index; 
 }

//==================== showList() =======================//

void SingleLinkedList::showList()
 {
  Link *current = first;
  
  while (current != NULL)
   {
    cout << "Data : " << current->data << endl;
    current = current->next;
   }    
 }
 
//======================================================//
//<<<<<<<<<<<<<<<<<<<<<< MAIN() >>>>>>>>>>>>>>>>>>>>>>>>//
//======================================================// 


int main(void)
 {
  SingleLinkedList list;
  
  list.insertFirst(4);
  list.insertFirst(8);
  list.insertFirst(16);
  list.insertFirst(111);
  list.insertFirst(55);
  
  list.showList();
  
  list.deleteDivisibleByFour();
  
  cout << "\n" << "After: " << "\n\n";
  
  list.showList();
  
  cout << "\n" << "Find (5): ";
  cout  << list.find(5) << "\n";
  
  system("pause");
  return EXIT_SUCCESS;
 }