disk

#include <stdio.h>
#include <stdlib.h>

#define up_bound 200 // Upper Bound
#define low_bound 0 // Lower Bound

int n, head; //n -> number of tracks, head -> starting position

void sort(int arr[], int size) { // Bubble Sort -> Ascending order
    for (int i = 0; i < size - 1; ++i) {
        for (int j = 0; j < size - i - 1; ++j) {
            if (arr[j] > arr[j + 1]) {
                int temp = arr[j];
                arr[j] = arr[j + 1];
                arr[j + 1] = temp;
            }
        }
    }
}

int findHead(int tracks[]) { // Find index of head from sorted array tracks[n+3]
    int position = 1;
    for (int i = 0; i < n + 3; ++i) {
        if (tracks[i] == head) {
            position = i;
            break;
        }
    }
    return position;
}

void FCFS(int tracks[]) { //Requests are processed in the order they arrive
    int sum = 0, current = head, new;  /* sum -> Total seek time
                                        * current -> to track the previously processed request
                                        * new -> absolute value of difference b/w previous and current request
                                        */
    printf("\nTraversed Order : { %d =>", head);
    for (int i = 0; i < n; ++i) {
        if (i < n - 1)
            printf(" %d =>", tracks[i]);
        else
            printf(" %d }", tracks[i]);
        new = current > tracks[i] ? current - tracks[i] : tracks[i] - current; /* if(current>head)
                                                                                    current - tracks[i]
                                                                                  else
                                                                                    tracks[i] - current */
        current = tracks[i];
        sum += new; // sum = sum + new
    }
    printf("\nTotal Head Movement = %d\n", sum);
}

void SCAN(int tracks[]) { /*moves the disk arm in one direction (either left or right) until it reaches the
                            end of the disk, When it reaches the end, it reverses direction and continues.*/
    int sum = 0, new, current; /* sum -> Total seek time
                                * current -> to track the previously processed request
                                * new -> absolute value of difference b/w previous and current request
                                */

    tracks[n] = head; // insert head, upper_bound and lower_bound to the sequence
    tracks[n + 1] = low_bound;
    tracks[n + 2] = up_bound;

    sort(tracks, n + 3); // sort array including the newly inserted values
    int head_pos = findHead(tracks); // find the index of head from the sorted array

    printf("\nTraversed Order : { %d =>", tracks[head_pos]);
    current = tracks[head_pos];

    for (int i = head_pos + 1; i < n + 3; ++i) { // Loop to calculate disk movement from head to upper_bound
        printf(" %d =>", tracks[i]);
        new = tracks[i] - current;
        current = tracks[i];
        sum += new;
    }
    for (int i = head_pos - 1; i > 0; i--) { //Loop to calculate disk movement from upper_bound to the least request
        if (i > 1)
            printf(" %d =>", tracks[i]);
        else
            printf(" %d }", tracks[i]);
        new = current - tracks[i];
        current = tracks[i];
        sum += new;
    }
    printf("\nTotal Head Movement = %d\n", sum);

}

void C_SCAN(int tracks[]) { /*Moves the disk arm in one direction (either left or right) until it reaches the
                            end of the disk, As soon as it reaches the other end, it immediately returns to the
                            beginning without servicing any requests, It then starts servicing requests again once
                            it reaches the beginning.*/
    int sum = 0, new, current;
    tracks[n] = head;
    tracks[n + 1] = low_bound;
    tracks[n + 2] = up_bound;
    sort(tracks, n + 3);
    int head_pos = findHead(tracks);

    printf("\nTraversed Order: { %d =>", tracks[head_pos]);
    current = tracks[head_pos];

    for (int i = head_pos + 1; i < n + 3; ++i) {
        printf(" %d =>", tracks[i]);
        new = tracks[i] - current;
        current = tracks[i];
        sum += new;
    }
    sum += current;
    current = tracks[0];
    for (int i = 0; i < head_pos; ++i) {
        if (i < head_pos - 1)
            printf(" %d =>", tracks[i]);
        else
            printf(" %d }", tracks[i]);
        new = tracks[i] - current;
        current = tracks[i];
        sum += new;
    }
    printf("\nTotal Head Movement = %d\n", sum);

}

int main() {
    while (1) {
        /////////////////////////////////////////////////
        printf("\nEnter number of tracks:");
        scanf("%d", &n);
        printf("Enter head position:");
        scanf("%d", &head);
        int tracks[n + 3]; // 3 index extra for inserting head, lower_bound and upper-bound
        printf("Enter %d sequence of tracks: ", n);
        for (int i = 0; i < n; ++i) {
            scanf("%d", &tracks[i]);
        }
        /////////////////////////////////////////////////
        int ch;
        printf("\nEnter your choice:\n1. FCFS\n2. SCAN\n3. C-Scan\n0. Exit\n");
        scanf("%d", &ch);
        switch (ch) {
            case 1:
                FCFS(tracks);
                break;
            case 2:
                SCAN(tracks);
                break;
            case 3:
                C_SCAN(tracks);
                break;
            case 0:
                exit(0);
            default:
                printf("Invalid Argument!");
        }
    }
}