programming-examples/java/Searching_Sorting_Algorithms/Java Program to Perform Searching Using Self-Organizing Lists.java

/*This is a java program to search an element using Self Organizing lists.
A self-organizing list is a list that reorders its elements based on some self-organizing heuristic to improve average access time.
The aim of a self-organizing list is to improve efficiency of linear search by moving more frequently accessed items towards the head of the list.
 A self-organizing list achieves near constant time for element access in the best case.
A self-organizing list uses a reorganizing algorithm to adapt to various query distributions at runtime.*/

//This is a java program to search an element in self organizing lists
import java.util.Random;
import java.util.Scanner;

class SelfOrganizingList
{
    private int[] list;
    private int[] count;
    private int size;

    public SelfOrganizingList(int listSize)
    {
        list = new int[listSize];
        count = new int[listSize];
        size = 0;
    }

    public boolean isEmpty()
    {
        return size == 0;
    }

    public boolean isFull()
    {
        return size == list.length;
    }

    public void makeEmpty()
    {
        int l = list.length;
        list = new int[l];
        count = new int[l];
        size = 0;
    }

    public int getSize()
    {
        return size;
    }

    public void insert(int val)
    {
        if (isFull())
            {
                System.out.println("Error : List full!");
                return;
            }
        list[size] = val;
        count[size] = 0;
        size++;
    }

    public void remove(int pos)
    {
        pos--;
        if (pos < 0 || pos >= size)
            {
                System.out.println("Invalid position ");
                return;
            }
        for (int i = pos; i < size - 1; i++)
            {
                list[i] = list[i + 1];
                count[i] = count[i + 1];
            }
        size--;
    }

    public boolean search(int x)
    {
        boolean searchResult = false;
        int pos = -1;
        for (int i = 0; i < size; i++)
            {
                if (list[i] == x)
                    {
                        searchResult = true;
                        pos = i;
                        break;
                    }
            }
        if (searchResult)
            {
                count[pos]++;
                int c = count[pos];
                for (int i = 0; i < pos; i++)
                    {
                        if (count[pos] > count[i])
                            {
                                for (int j = pos; j > i; j--)
                                    {
                                        list[j] = list[j - 1];
                                        count[j] = count[j - 1];
                                    }
                                list[i] = x;
                                count[i] = c;
                                break;
                            }
                    }
            }
        return searchResult;
    }

    public void printList()
    {
        System.out.print("\nList = ");
        for (int i = 0; i < size; i++)
            System.out.print(list[i] + " ");
        System.out.print("\nCount = ");
        for (int i = 0; i < size; i++)
            System.out.print(count[i] + " ");
    }
}

public class Search_Self_Organizing
{
    public static void main(String[] args)
    {
        Random random = new Random();
        int N = 20;
        SelfOrganizingList list = new SelfOrganizingList(N);
        for (int i = 0; i < N; i++)
            list.insert(Math.abs(random.nextInt(1000)));
        Scanner scan = new Scanner(System.in);
        System.out.println("SelfOrganizingList Searching \n");
        list.printList();
        System.out.println("\nEnter integer element to search");
        System.out.println("Search Result : " + list.search(scan.nextInt()));
        scan.close();
    }
}
/*

List = 855 318 462 851 373 360 811 401 813 50 291 346 707 118 633 217 715 594 999 99
Count = 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Enter integer element to search
811
Search Result : true