Program:
#include <stdio.h>
#include<stdlib.h>
// Function to Sort Array
void sort(int arr[],int n){
for(int i=0;i<n;i++){
for(int j=0;j<n-i-1;j++){
if(arr[j]>arr[j+1]){
int temp = arr[j];
arr[j] = arr[j+1];
arr[j+1] = temp;
}
}
}
}
// CLook
// In this we go in one direction and after that
// comeback to first unvisited of other direction
// and goes into increment
void CLook()
{
int n;
printf("Enter number of disk requests : \n");
scanf("%d",&n);
int req[n];
printf("Enter the sequence of requests : \n");
for(int i=0;i<n;i++)
scanf("%d",&req[i]);
int initial;
printf("Enter the initial position of the head : \n");
scanf("%d",&initial);
int m;
printf("Enter the direction of movement of the head : 1.High 0.Low \n");
scanf("%d",&m);
sort(req,n);
int totalSeekTime = 0;
// finding intial index
int idx;
for(idx=0;idx<n;idx++){
if(initial<req[idx])
break;
}
// Going in High Direction
if(m)
{
// In this we go in one direction from index to end
for(int i=idx;i<n;i++)
{
totalSeekTime += abs(req[i] - initial);
printf("seek time between %d and %d is %d\n",req[i],initial,abs(req[i]- initial));
initial = req[i];
}
// In this we go from 0 to index
for(int i=0;i<idx;i++)
{
totalSeekTime += abs(req[i] - initial);
printf("seek time between %d and %d is %d\n",req[i],initial,abs(req[i]- initial));
initial = req[i];
}
}
else
{
for(int i=idx-1;i>=0;i--)
{
totalSeekTime += abs(req[i] - initial);
printf("seek time between %d and %d is %d\n",req[i],initial,abs(req[i]- initial));
initial = req[i];
}
for(int i=n-1;i>=idx;i--)
{
totalSeekTime += abs(req[i] - initial);
printf("seek time between %d and %d is %d\n",req[i],initial,abs(req[i]- initial));
initial = req[i];
}
}
printf("\nTotal seek time is : %d\n", totalSeekTime);
printf("\nAverage seek time is : %f\n" , totalSeekTime/(0.1*10*n));
}
// SCAN (Elevator)
/*
We go in One Direction and goes to end of it
and while coming back we visit unvisited.
*/
void Scan()
{
int n;
printf("Enter the number of processes : \n");
scanf("%d",&n);
int size;
printf("Enter the size of the disk : \n");
scanf("%d",&size);
int req[n];
printf("Enter the sequence of requests : \n");
for(int i=0;i<n;i++)
scanf("%d",&req[i]);
int initial;
printf("Enter the initial position of the head : \n");
scanf("%d",&initial);
int m;
printf("Enter the direction of movement of the head : 1.Right 0.Left \n");
scanf("%d",&m);
sort(req,n);
int idx;
for(idx=0;idx<n;idx++)
{
if(initial<req[idx])
break;
}
int totalSeekTime = 0;
int i;
// 1- Right
if(m)
{
// Going in One Direction
for(i=idx;i<n;i++)
{
totalSeekTime += abs(req[i] - initial);
initial = req[i];
}
// going to end of the disk
totalSeekTime += abs(size - req[i-1] - 1);
initial = size - 1;
// while coming back visit the unvisited
for(i=idx-1;i>=0;i--)
{
totalSeekTime += abs(req[i] - initial);
initial = req[i];
}
}
else
{
for(i=idx-1;i>=0;i--)
{
totalSeekTime += abs(req[i] - initial);
initial = req[i];
}
totalSeekTime += abs(req[i+1] - 0);
initial = 0;
for(i=idx;i<n;i++)
{
totalSeekTime += abs(req[i] - initial);
initial = req[i];
}
}
printf("Total seek time is : %d",totalSeekTime);
}
// SSTF (Shortest Seek Time First)
/*
We visit the Track which is shortest to current track
*/
void Sstf()
{
int n;
printf("Enter number of disk requests : \n");
scanf("%d",&n);
int req[n];
printf("Enter the sequence of requests : \n");
for(int i=0;i<n;i++)
scanf("%d",&req[i]);
int initial;
printf("Enter the initial position of the head : \n");
scanf("%d",&initial);
int totalSeekTime = 0;
int cnt = 0;
while(cnt!=n)
{
int min = 10000, idx;
// in this we are finding minimum difference from current head
for(int i=0;i<n;i++)
{
int diff = abs(req[i] - initial);
if(min>diff)
{
min = diff;
idx = i;
}
}
totalSeekTime += min;
// Updating Inital
initial = req[idx];
// Increased time of visited
req[idx] = 1000;
// counting total number of tracks visited
cnt++;
}
printf("Total seek time : %d\n", totalSeekTime);
}
int main()
{
int ch;
printf("\n\n Menu:");
printf("\n 1) CLOOK ");
printf("\n 2) SSTF ");
printf("\n 3) SCAN ");
printf("\n\n Enter Choice:");
scanf("%d",&ch);
switch (ch)
{
case 1:
CLook();
break;
case 2:
Sstf();
break;
case 3:
Scan();
break;
default:
break;
}
return 0;
}
Output:
