R. R

#include<stdio.h>
struct process
{
char name;
int at,bt,wt,tt,rt;
int completed;
float ntt;
}p[10];

int n;
int q[10];  //queue
int front=-1,rear=-1;

void enqueue(int i)
{
if(rear==10)
printf("overflow");
rear++;
q[rear]=i;
if(front==-1)
front=0;

}

int dequeue()
{
if(front==-1)
printf("underflow");
int temp=q[front];
if(front==rear)
front=rear=-1;
else
front++;
return temp;
}

int isInQueue(int i)
{int k;
for(k=front;k<=rear;k++)
{
if(q[k]==i)
return 1;
}
return 0;

}

void sortByArrival()
{
struct process temp;
int i,j;
for(i=0;i<n-1;i++)
for(j=i+1;j<n;j++)
{
if(p[i].at>p[j].at)
{
temp=p[i];
p[i]=p[j];
p[j]=temp;
}
}
}

void main()
{
int i,j,time=0,sum_bt=0,tq;
char c;
        float avgtt=0;
 printf("Enter no of processes:");
 scanf("%d",&n);
 for(i=0,c='A';i<n;i++,c++)
 {
 p[i].name=c;
 printf("\nEnter the arrival time and burst time of process %c: ",p[i].name);
 scanf("%d%d",&p[i].at,&p[i].bt);
 p[i].rt=p[i].bt;
 p[i].completed=0;
 sum_bt+=p[i].bt;

}

printf("\nEnter the time quantum:");
scanf("%d",&tq);

sortByArrival();
enqueue(0);          // enqueue the first process
printf("Process execution order: ");
for(time=p[0].at;time<sum_bt;)       // run until the total burst time reached
{   i=dequeue();

if(p[i].rt<=tq)
{                          /* for processes having remaining time with less than or equal to time quantum  */

time+=p[i].rt;
p[i].rt=0;
p[i].completed=1;
    printf(" %c ",p[i].name);
            p[i].wt=time-p[i].at-p[i].bt;
            p[i].tt=time-p[i].at;
            p[i].ntt=((float)p[i].tt/p[i].bt);
            for(j=0;j<n;j++)                /*enqueue the processes which have come while scheduling */
            {
            if(p[j].at<=time && p[j].completed!=1&& isInQueue(j)!=1)
            {
            enqueue(j);

            }
           }
        }
    else               // more than time quantum
    {
    time+=tq;
    p[i].rt-=tq;
    printf(" %c ",p[i].name);
    for(j=0;j<n;j++)    /*first enqueue the processes which have come while                                             scheduling */
            {
            if(p[j].at<=time && p[j].completed!=1&&i!=j&& isInQueue(j)!=1)
             {
            enqueue(j);

            }
           }
           enqueue(i);   // then enqueue the uncompleted process

    }



}

printf("\nName\tArrival Time\tBurst Time\tWaiting Time\tTurnAround Time\t Normalized TT");
for(i=0;i<n;i++)
{avgtt+=p[i].tt;
printf("\n%c\t\t%d\t\t%d\t\t%d\t\t%d\t\t%f",p[i].name,p[i].at,p[i].bt,p[i].wt,p[i].tt,p[i].ntt);
}

printf("\nAverage turnaround time:%.2f\n",avgtt/n);
}