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sjf_sa_np_vp.cpp
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sjf_sa_np_vp.cpp
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// C++ Program to demonstrate the working of Shortest Job First Scheduling Algorithm
// it consider the arrival time in and out order
// by Vijay Purohit
// working and tested on Dev-C++ 5.11
#include<stdio.h>
#include<iostream>
#include<cstdlib>
#include<cstdio>
using namespace std;
typedef struct process
{
int id; // process id
int at; // process arrival time
int bt; // process burst time
int rt; // process remaining time after completing time quantum
int st; // process starting time
int ft; // process finish time
float wt,tat; // process waiting time and time quantum
}process;
process p[20],ps[20],temp; // main process and ps= process sorted.
int accept() //functions for accepting inputs from the user
{
int i,n;
cout<<"Enter total number of processes(maximum 20):";
cin>>n;
if(n==0){
cout<<"\nInvalid no. of process"; exit(1);
}
for(i=1;i<=n;i++)
{
cout<<"\nEnter Arrival Time and Burst Time for Process P["<<i<<"] : Ar :";
p[i].id=i; // storing process id or no
cin>>p[i].at;
cout<<"\t\t\t\t\t\t Ex: ";
cin>>p[i].bt;
p[i].rt=p[i].bt; // copying burst time to remaining time
ps[i]=p[i]; // copying of one process into another process(dummy process)
}
return n;
}
void sort_arrival(int n)
{
int i,j;
for(i=2;i<=n;i++)
for(j=1;j<i;j++)
if(ps[j].at>ps[i].at)
{
temp=ps[i];
ps[i]=ps[j];
ps[j]=temp;
}
else if(ps[j].at==ps[i].at) //if both the arrival time are equal then sort on the basis of process burst time
if(ps[j].bt>ps[i].bt)
{
temp=ps[i];
ps[i]=ps[j];
ps[j]=temp;
}
}
main()
{
int i, j=1, k, l, n, m, time=0;
float sum_waittime=0, sum_turnaround=0;
int ganttP[50],ganttStartTime[50], ganttStopTime[50];
cout << fixed;
cout.precision(2);
n=accept();
sort_arrival(n);
time = ps[1].at; // starting time is equal to arrival time for first process
for(i=1;i<=n;i++)
{
ganttP[j] = m = ps[i].id; // process no
// ps[i].st = ps[i-1].st + ps[i-1].bt;
ganttStartTime[j] = p[m].st = ps[i].st = time; // process (unsorted) and process sorted
// time = p[m].ft = ps[i].ft = ps[i].st + ps[i].bt;
time += ps[i].bt; // it will execute till its burst time
ganttStopTime[j++] = p[m].ft = ps[i].ft = time;
if( ps[i+1].at > ps[i].ft ) // if next process arrival time is greater than current process finish time
time = ps[i+1].at;
else
{
for(k=i+1 ; k<=n && ps[k].at <= time ; k++ ) // sorting the remaining process according to their min burst time
{
for(l=k+1 ; l<=n && ps[l].at <= time; l++)
if(ps[l].bt < ps[k].bt)
{
temp=ps[l];
ps[l]=ps[k];
ps[k]=temp;
}
}
}
//calculating waiting time
p[m].tat = p[m].ft - p[m].at;
p[m].wt = p[m].tat - p[m].bt;
sum_turnaround += p[m].tat;
sum_waittime += p[m].wt;
}
cout<<"\n Gantt Chart is = P[NO](start time, stop time) : \n";
for(i=1;i<j;i++)
{
printf("p[%d](%d,%d) || ", ganttP[i], ganttStartTime[i], ganttStopTime[i]);
}
printf("\n===========================/=================================");
printf("\n\nProcess\t | Arrival Time | Waiting Time | Completion T | Turnaround T | \n\n");
for(i=1;i<=n;i++)
{
printf(" P[%d] \t|\t %d\t|\t %.2f\t|\t %d \t|\t %.2f |\n",p[i].id, p[i].at, p[i].wt, p[i].ft, p[i].tat);
}
cout<<"\nAverage Waiting Time = "<<sum_waittime/n;
cout<<"\nAvg TurnAround Time = "<<sum_turnaround/n;
}