Question

Implement a program for SJF(non-preemptive) scheduling. Given n processes with their burst times and Arrival Time, the task is to find average waiting time and average turn around time and completion time using SJF scheduling algorithm. Language in C

• Completion Time: Time at which process completes its execution.

• Turn Around Time: Time Difference between completion time and arrival time. Turn Around Time = Completion Time – Arrival Time

• Waiting Time: Time Difference between turn around time and burst time. Waiting Time = Turn Around Time – Burst Time

Answer 1

Here is a program for the implementation of SJF (Non-preemptive) scheduling.
#include<iostream>
using namespace std;
int mat[10][6];

void swap(int *a, int *b)
{
   int temp = *a;
   *a = *b;
   *b = temp;
}

void arrangeArrival(int num, int mat[][6])
{
   for(int i=0; i<num; i++)
   {
       for(int j=0; j<num-i-1; j++)
       {
           if(mat[j][1] > mat[j+1][1])
           {
               for(int k=0; k<5; k++)
               {
                   swap(mat[j][k], mat[j+1][k]);
               }
           }
       }
   }
}

void completionTime(int num, int mat[][6])
{
   int temp, val;
   mat[0][3] = mat[0][1] + mat[0][2];
   mat[0][5] = mat[0][3] - mat[0][1];
   mat[0][4] = mat[0][5] - mat[0][2];
  
   for(int i=1; i<num; i++)
   {
       temp = mat[i-1][3];
       int low = mat[i][2];
       for(int j=i; j<num; j++)
       {
           if(temp >= mat[j][1] && low >= mat[j][2])
           {
               low = mat[j][2];
               val = j;
           }
       }
       mat[val][3] = temp + mat[val][2];
       mat[val][5] = mat[val][3] - mat[val][1];
       mat[val][4] = mat[val][5] - mat[val][2];
       for(int k=0; k<6; k++)
       {
           swap(mat[val][k], mat[i][k]);
       }
   }
}

int main()
{
   int num, temp;
  
   cout<<"Enter number of Process: ";
   cin>>num;
  
   cout<<"...Enter the process ID...\n";
   for(int i=0; i<num; i++)
   {
       cout<<"...Process "<<i+1<<"...\n";
       cout<<"Enter Process Id: ";
       cin>>mat[i][0];
       cout<<"Enter Arrival Time: ";
       cin>>mat[i][1];
       cout<<"Enter Burst Time: ";
       cin>>mat[i][2];
   }
  
   cout<<"Before Arrange...\n";
   cout<<"Process ID\tArrival Time\tBurst Time\n";
   for(int i=0; i<num; i++)
   {
       cout<<mat[i][0]<<"\t\t"<<mat[i][1]<<"\t\t"<<mat[i][2]<<"\n";
   }
  
   arrangeArrival(num, mat);
   completionTime(num, mat);
   cout<<"Final Result...\n";
   cout<<"Process ID\tArrival Time\tBurst Time\tWaiting Time\tTurnaround Time\n";
   for(int i=0; i<num; i++)
   {
       cout<<mat[i][0]<<"\t\t"<<mat[i][1]<<"\t\t"<<mat[i][2]<<"\t\t"<<mat[i][4]<<"\t\t"<<mat[i][5]<<"\n";
   }
}