DISKSHED_SCAN.cpp

#include <iostream>
#include <algorithm>
#include <cmath>

using namespace std;

int callSCAN(int arr[], int init, int maxreq, int len, bool isLeft) {
    int sum = 0;

    // Sorting the requests
    sort(arr, arr + len);

    // Finding the virtual location of init in the request array
    int pos = lower_bound(arr, arr + len, init) - arr;

    int left = pos - 1;
    int right = pos;

    // Moving towards the specified direction (left or right)
    if (isLeft) {
        // Moving towards the left side first in the array
        sum += abs(init - arr[left]);
        cout << arr[left] << endl;

        while (left != 0) {
            sum += abs(arr[left] - arr[left - 1]);
            cout << arr[left - 1] << endl;
            left--;
        }

        // Moving to track 0
        sum += arr[0];
        cout << "0" << endl;

        // Now moving towards the right direction
        sum += abs(0 - arr[right]);
        cout << arr[right] << endl;

        while (right < len - 1) {
            sum += abs(arr[right] - arr[right + 1]);
            cout << arr[right + 1] << endl;
            right++;
        }
    } else {
        // Moving towards the right side first in the array
        sum += abs(init - arr[right]);
        cout << arr[right] << endl;

        while (right < len - 1) {
            sum += abs(arr[right] - arr[right + 1]);
            cout << arr[right + 1] << endl;
            right++;
        }

        // Moving to the maximum possible track request from where the head will reverse its direction
        sum += abs(arr[len - 1] - maxreq);
        cout << maxreq << endl;

        // Now moving towards the left direction
        sum += abs(maxreq - arr[left]);
        cout << arr[left] << endl;

        while (left != 0) {
            sum += abs(arr[left] - arr[left - 1]);
            cout << arr[left - 1] << endl;
            left--;
        }
    }

    return sum;
}

int main() {
    int maxreq;
    cout << "Enter the maximum number of cylinders: ";
    cin >> maxreq;

    int len;
    cout << "Enter the number of disk requests: ";
    cin >> len;

    int arr[len];
    cout << "Enter the disk request queue: ";
    for (int i = 0; i < len; ++i) {
        cout << "Request " << (i + 1) << ":";
        cin >> arr[i];
    }

    int init;
    cout << "Enter the current head position: ";
    cin >> init;

    char direction;
    cout << "Enter the direction of movement (L for left, R for right): ";
    cin >> direction;

    bool isLeft = false;
    if (direction == 'L' || direction == 'l') {
        isLeft = true;
    }

    int res = callSCAN(arr, init, maxreq, len, isLeft);
    cout << "Total Head Movement: " << res << endl;

    float tpt = (float)len / (float)res;
    cout << "Throughput: " << tpt << endl;

    return 0;
}