C++ Program For LOOK Disk Scheduling Algorithm

Look Disk Scheduling Algorithm

LOOK Algorithm is an improved version of the SCAN Algorithm.
Head starts from the first request at one end of the disk and moves towards the last request at the other end servicing all the requests in between.
After reaching the last request at the other end, the head reverses its direction.
It then returns to the first request at the starting end servicing all the requests in between.
The same process repeats.

#include <iostream>

#include <stdlib.h>

using namespace std;

class look_disk

{

    int ref[100];

    int ttrk, cur, size, prev;

    int sort();

public:
    void getdata();

    void total_move();
};

int look_disk::sort()

{

    int temp;

    for (int i = 0; i < size - 1; i++)

        for (int y = 0; y < size - 1; y++)

            if (ref[y] > ref[y + 1])

            {

                temp = ref[y + 1];

                ref[y + 1] = ref[y];

                ref[y] = temp;
            }

    for (int i = 0; i < size; i++)

        if (ref[i] > cur)

            return i;

    return size;
}

void look_disk::getdata()

{

    cout << "Enter total number of tracks : ";

    cin >> ttrk;

    ttrk--;

    cout << "Enter the current position of head : ";

    cin >> cur;

    cout << "Enter previous position of head : ";

    cin >> prev;

    cout << "Enter the size of queue : ";

    cin >> size;

    cout << "Enter the request for tracks : ";

    for (int i = 0; i < size; i++)

        cin >> ref[i];
}

void look_disk::total_move()

{

    int num = cur, move = 0, ind, dir = cur - prev;

    ind = sort();

    if (dir > 0)

    {

        for (int i = ind; i < size; i++)

        {

            move += ref[i] - num;

            num = ref[i];
        }

        if (ind != 0)

        {

            if (ind == size)

                move += num - ref[ind - 1];

            else

                move += ref[size - 1] - ref[ind - 1];

            num = ref[ind - 1];

            for (int i = ind - 2; i >= 0; i--)

            {

                move += num - ref[i];

                num = ref[i];
            }
        }
    }

    else

    {

        for (int i = ind - 1; i >= 0; i--)

        {

            move += num - ref[i];

            num = ref[i];
        }

        if (ind == 0)

            move += ref[ind] - num;

        else if (ind != size)

            move += ref[ind] - ref[0];

        num = ref[ind];

        for (int i = ind + 1; i < size; i++)

        {

            move += ref[i] - num;

            num = ref[i];
        }
    }

    cout << "Total head movements : " << move;
}

int main()

{

    look_disk look;

    look.getdata();

    look.total_move();

    return 0;
}