#include<stdio.h>
#include<stdlib.h>
#define MAX 5
#define TRUE 1
#define FALSE 0
struct QType
{
int time;
int a_time;
int priority;
int executions_no;
int p_id;
struct QType * next;
};
struct QType *front;
struct QType *rear;
///////////////////////////////////////////////////////////////////////
int awt,sum_time,wt,p_no,Quantum;  //external variables
int arr[30];
///////////////////////////////////////////////////////////////////////
int empty()
{
if (front == NULL && rear == NULL)
return TRUE;
else return FALSE;
}
///////////////////////////////////////////////////////////////////////
void addQ(int t_time,int t_a_time,int t_priority)
{
 struct QType * ptr = (struct QType *) malloc(sizeof(struct QType));
 ptr->time=t_time;
 ptr->a_time=t_a_time;
 ptr->priority=t_priority;
 ptr->executions_no=0;
 ptr->next=NULL;
 if (empty())
   {
    rear = ptr;
    front = ptr;
   }
  else
    {
     rear->next=ptr;
     rear = ptr;
    }
}
/////////////////////////////////////////////////////////////////////
int delQ()
{
 int item;
 if (empty())
  {
   printf("Empty\n");
   return(-1);
  }
  else
   {
    struct QType * ptr;
    ptr = front;
    front=front->next;
    item=ptr->time;
    free(ptr);
    return(item) ;
   }
}
////////////////////////////////////////////////////////////////////////
void showQ()
{
 struct QType * sFront = front ;
 printf("\nQ = [") ;
 while( sFront != NULL )
     {
      printf("%d,",sFront->time);
      sFront = sFront->next;
     }
 printf("\b]\n");
}
//////////////////////////////////////////////////////////////////////
void sortQ()
{
 int p,t,a,id;
 struct QType *i,*j=front;
 for(i=front;i!=NULL;i=i->next)
    for(j=i;j!=NULL;j=j->next)
      {
	if(i->time>j->time)
	 {
	   p=i->priority;
	   t=i->time;
	   a=i->a_time;
	   id=i->p_id;
	   i->priority=j->priority;
	   i->time=j->time;
	   i->a_time=j->a_time;
	   i->p_id=j->p_id;
	   j->priority=p;
	   j->time=t;
	   j->a_time=a;
	   j->p_id=id;
	 }
      }
}
/////////////////////////////////////////////////////////////////////////
void priority_sortQ()
{
 int p,t,a,id;
 struct QType *i,*j=front;
 for(i=front;i!=NULL;i=i->next)
    for(j=i;j!=NULL;j=j->next)
      {
	if(i->priority<j->priority)
	 {
	   p=i->priority;
	   t=i->time;
	   a=i->a_time;
	   id=i->p_id;
	   i->priority=j->priority;
	   i->time=j->time;
	   i->a_time=j->a_time;
	   i->p_id=j->p_id;
	   j->priority=p;
	   j->time=t;
	   j->a_time=a;
	   j->p_id=id;
	 }
      }
 
}
/////////////////////////////////////////////////////////////////////
void choose()
{
    int i,time,a_time,priority;
    clrscr();
    printf("\nWhat's the number of the processes you want to execute? ");
    scanf("%d",&p_no);
    printf("\nEnter the time Quantum for the Round Robin Scheduling ");
    scanf("%d",&Quantum);
    for(i=1;i<=p_no;i++)
      {
       printf("\n///////////////////////////////////////////////////////////");
       printf("\nEnter the time needed for process No. %d ",i);
       scanf("%d",&time);
       printf("\nEnter the process arrival time ");
       scanf("%d",&a_time);
       printf("\nEnter the priority of this process ");
       scanf("%d",&priority);
       addQ(time,a_time,priority);
       rear->p_id=i;
       arr[i]=time;       //for the Round Robin sch.
       }
}
/////////////////////////////////////////////////////////////////////////
void FCFS()
{
 int x=p_no;
 struct QType * F;
  awt=wt=0;
  F=front;
  x=p_no-1;
  while(F->next!=NULL)
    {
      wt+=F->time;
      awt+=x*F->time;
      printf("\nwt for process %d= %d ",++F->p_id,wt);
      x--;
      F=F->next;
    }
  showQ();
  printf("\nawt= %0.2f Ms",(float)awt/p_no,"\n\n");
}
/////////////////////////////////////////////////////////////////////////
void SJF()
{
 int i;
 struct QType * F;
 awt=wt=0;
 front=rear=NULL;
  for(i=1;i<=p_no;i++)
      {
       addQ(arr[i],0,0);
       rear->p_id=i;
	}
  F=front;
  sortQ();
  while(F->next!=NULL)
    {
      wt+=F->time;
      awt+=wt;
      F=F->next;
      printf("\n the waiting time for %d process is %d",F->p_id,wt);
    }
  printf("\nawt= %0.2f Ms",(float)awt/p_no,"\n\n");
}
/////////////////////////////////////////////////////////////////////////
void PRIORITY()
{
 int x,i;
 struct QType * front1=front;
 sum_time=awt=0;
  x=p_no-1;
  printf("\nPRIORITY\nThe procecess will execute in this order ");
  while(front1->next!=NULL)
    {
      priority_sortQ();
ex:   front1=front;
      if(can_exe(front1->a_time))
	{
	  sum_time+=front1->time;
	  awt+=x*front1->time;
	  awt=awt-front1->a_time;
	  x--;
	  printf("%d  ",delQ());
	}
      else
	{
	  addQ(front->time,front->a_time,front->priority);
	  delQ();
	  goto ex;
	}
    }
 // delQ();
  printf("\nawt= %0.2f Ms",(float)awt/p_no,"\n\n");
}
/////////////////////////////////////////////////////////////////////////
int can_exe(int item)
{
 struct QType *ptr=front;
  int x=0;
  for(ptr=front;ptr!=NULL;ptr=ptr->next)
     {
      if(item<=sum_time)
      x=1;
     }
  return x;
}
/////////////////////////////////////////////////////////////////////////
void ROUND_ROBIN()
{
  int temp,i=0;
  sum_time=awt=wt=0;
 front=rear=NULL;
 for(i=1;i<=p_no;i++)
      {
       addQ(arr[i],0,0);
       rear->p_id=i;
	}
 printf("\nROUND ROBIN\n");
 while(front!=NULL)
     {
       if(front->time>Quantum)
	 {
	   temp=front->time;
	   front->executions_no++;
	   front->time=Quantum;
	   addQ(temp-front->time,0,0);
	   rear->executions_no=front->executions_no++;
	   rear->p_id=front->p_id;
	   sum_time+=front->time;
	   delQ();
	 }
       else
	 {
	   wt=sum_time-(front->executions_no*Quantum);
	   printf("\nThe waiting time for the process %d = %d",front->p_id,wt);
	   sum_time+=front->time;
	   awt+=wt;
	   delQ();
	 }
  }
   printf("\nThe avg. waiting time is %0.2f",(float)awt/p_no);
}
/////////////////////////////////////////////////////////////////////////
void main()
{
int ch;
char stop;
choose();
printf("\n1- PRESS TO VIEW THE REPORT ");
printf("\n2- Enter new other data ");
printf("\n3- Exit");
scanf("%d",&ch);
switch(ch)
  {
    case 1:
	    printf("\nFCFS//////////////////////////////////////\n");
	    FCFS();
	    printf("\n\n\n\nPRIORITY//////////////////////////////////\n");
	    PRIORITY();
	    printf("\n\n\n\nSJF///////////////////////////////////////\n");
	    SJF();
	    printf("\n\n\n\nROUND_ROBIN////////////////////////////////\n");
	    ROUND_ROBIN();
	    printf("\n\n\n\n\n\n\n\n\n\nENTER ANY NO. TO EXIT ");
	    scanf("%d",wt);//working as getche() function//
	    break;
     case 2:
	    choose();
	    break;
     case 3:
	    break;
    }
}