Multilevel Queue Feedback CPU Scheduling Algorithm

#include<stdio.h>
#include<conio.h>

float avg_wt,avg_tt;
int i = 0,ttl_wt=0,ttl_tt=0,qt1=4,qt2=8;

struct process
{
 int prn;
 char type;
 int bt;
 int wt;
 int tt;
 struct process *nxt;
}*stfor1,*stfor2,*stbck,*np,*endfor1,*endfor2,*endbck,*temp;

void ins_node(struct process *np,int num)
{
 if(num == 1)
 {
  if(stfor1 == NULL)
    stfor1 = endfor1 = np;
  else
  {
   endfor1->nxt = np;
   endfor1 = np;
  }
 }
 else if(num == 2)
 {
  if(stfor2 == NULL)
    stfor2 = endfor2 = np;
  else
  {
   endfor2->nxt = np;
   endfor2 = np;
  }
 }
 else
 {
  if(stbck == NULL)
    stbck = endbck = np;
  else
  {
   endbck->nxt = np;
   endbck = np;
  }
 }
}

void del_node(struct process *np,int num,int choice)
{
 if(num == 1)
 {
  if(stfor1 == endfor1)
   stfor1 = NULL;
  else
   stfor1 = stfor1->nxt;
  if(choice == 1)
   delete np;
 }
 else if(num == 2)
 {
  if(stfor2 == endfor2)
   stfor2 = NULL;
  else
   stfor2 = stfor2->nxt;
  if(choice == 1)
   delete np;
 }
 else
 {
  if(stbck == endbck)
   stbck = NULL;
  else
   stbck = stbck->nxt;
  delete np;
 }
}

void ins_dat()
{
  char ch;
  int j=0,n;
  stfor1 = endfor1 = stfor2 = endfor2 = stbck = endbck = NULL;
  do
  {
  np = new process;
  np->nxt = NULL;
  np->prn = ++j;
  printf("\n Enter the Burst time of Process #%d : ",np->prn);
  scanf("%d",&np->bt);
  printf("\n Enter the type of Process #%d (f-foreground or b-background): ",np->prn);
  np->type = getche();

  if(np->type == 'f')
   np->nxt = stfor1;
  else
   np->nxt = NULL;

  np->wt = np->tt = 0;
  if(np->type == 'f')
   ins_node(np,1);
  else
   ins_node(np,3);
  printf("\n\n Continue ?? : ");
  ch = getche();
  }while(ch == 'y' || stfor1 == NULL);
}

void Round_Robin()
{
 getch();
 printf("\n\n Foreground RR Process Scheduling (Quantum Size = %d)\n\n",qt1);
 printf("\n\n Process   Burst Time   Waiting Time   Turnaround Time \n");
 printf(" ------------------------------------------------------- \n");
 temp = stfor1;
  do
  {
   printf(" %d \t\t %d \t\t",stfor1->prn,stfor1->bt);
   stfor1->wt += (temp->tt - stfor1->tt);
   if(qt1 >= stfor1->bt)
   {
    stfor1->tt = temp->tt + stfor1->bt;
    stfor1->bt = 0;
    printf(" %d \t\t %d\n\n",stfor1->wt,stfor1->tt);
    ttl_wt += stfor1->wt;
    ttl_tt += stfor1->tt;
    temp = np = stfor1;
    del_node(np,1,1);
    ++i;
   }
   else
   {
    stfor1->bt -= qt1;
    stfor1->tt = temp->tt + qt1;
    printf(" %d \t\t %d\n\n",stfor1->wt,stfor1->tt);
    temp = np = stfor1;
    del_node(np,1,2);
    if(temp->bt > qt1)
     ins_node(temp,2);
    else
     ins_node(temp,1);
   }
  }while(stfor1 != NULL);


  if(stfor1 == NULL && stfor2 != NULL)
  {
  getch();
  printf("\n Foreground RR Process Scheduling (Quantum Size = %d)\n",qt2);
  printf("\n\n Process   Burst Time   Waiting Time   Turnaround Time \n");
  printf(" ------------------------------------------------------- \n");
  do
  {
   printf(" %d \t\t %d \t\t",stfor2->prn,stfor2->bt);
   stfor2->wt += (temp->tt - stfor2->tt);
   if(qt2 >= stfor2->bt)
   {
    stfor2->tt = temp->tt + stfor2->bt;
    stfor2->bt = 0;
    printf(" %d \t\t %d\n\n",stfor2->wt,stfor2->tt);
    ttl_wt += stfor2->wt;
    ttl_tt += stfor2->tt;
    temp = np = stfor2;
    del_node(np,2,1);
    ++i;
   }
   else
   {
    stfor2->bt -= qt2;
    stfor2->tt = temp->tt + qt2;
    printf(" %d \t\t %d\n\n",stfor2->wt,stfor2->tt);
    np = temp = stfor2;
    del_node(np,2,2);
    if(temp->bt > qt2)
     ins_node(temp,3);
    else
     ins_node(temp,2);
   }
  }while(stfor2 != NULL);
  }
}

void FCFS()
{
 getch();
 printf("\n\n Background FCFS Process Scheduling \n\n");
 printf("\n\n Process   Burst Time   Waiting Time   Turnaround Time \n");
 printf(" ------------------------------------------------------- \n");
 do
 {
   printf(" %d \t\t %d \t\t",stbck->prn,stbck->bt);
   stbck->wt += (temp->tt-stbck->tt);
   stbck->tt = temp->tt + stbck->bt;
   printf(" %d \t\t %d\n\n",stbck->wt,stbck->tt);
   ttl_wt += stbck->wt;
   ttl_tt += stbck->tt;
   temp = np = stbck;
   del_node(np,3,1);
   ++i;
 }while(stbck != NULL);

}
void main()
{
 clrscr();
 ins_dat();
 if(stfor1 != NULL)
  Round_Robin();
 if(stfor1 == NULL && stfor2 == NULL && stbck != NULL)
  FCFS();
 avg_wt = (float) ttl_wt/i;
 avg_tt = (float) ttl_tt/i;
 printf("\n\n Average Waiting Time  : %f",avg_wt);
 printf("\n Average Turnaround Time : %f",avg_tt);
 getch();
}