a)

private void expand()
{
 int length = size();
 int[] newQ = new int[length<<1];
 for(int i=front; i<=rear; i++)
 {
  newQ[i-front] = Q[i%CAPACITY];
 }
 Q = newQ;
 front = 0;
 rear = size()-1;
}

b)

private void expand()
{
 int length = size();
 int[] newQ = new int[length<<1];
 for(int i=front; i<=rear; i++)
 {
  newQ[i-front] = Q[i%CAPACITY];
 }
 Q = newQ;
}

c)

private void expand()
{
 int length = size();
 int[] newQ = new int[length<<1];
 for(int i=front; i<=rear; i++)
 {
  newQ[i-front] = Q[i];
 }
 Q = newQ;
 front = 0;
 rear = size()-1;
}

d)

private void expand()
{
 int length = size();
 int[] newQ = new int[length*2];
 for(int i=front; i<=rear; i++)
 {
  newQ[i-front] = Q[i%CAPACITY];
 }
 Q = newQ;
}

public class CircularQueue
{
 protected static final int CAPACITY = 100;
 protected int size,front,rear;
 protected Object q[];
 int count = 0;
 
 public CircularQueue()
 {
  this(CAPACITY);
 }
 public CircularQueue (int n)
 {
  size = n;
  front = 0;
  rear = 0;
  q = new Object[size];
 }
 
 
 public void enqueue(Object item)
 {
  if(count == size)
  {
   System.out.println("Queue overflow");
    return;
  }
  else
  {
   q[rear] = item;
   rear = (rear+1)%size;
   count++;
  }
 }
 public Object dequeue()
 {
  if(count == 0)
  {
   System.out.println("Queue underflow");
   return 0;
  }
  else
  {
   Object ele = q[front];
   q[front] = null;
   front = (front+1)%size;
   count--;
   return ele;
  }
 }
 public Object frontElement()
 {
  if(count == 0)
  return -999;
  else
  {
   Object high;
   high = q[front];
   return high;
  }
 }
 public Object rearElement()
 {
  if(count == 0)
  return -999;
  else
  {
   Object low;
   rear = (rear-1)%size;
   low = q[rear];
   rear = (rear+1)%size;
   return low;
  }
 }
}
public class CircularQueueDemo
{
 public static void main(String args[])
 {
  Object var;
  CircularQueue myQ = new CircularQueue();
  myQ.enqueue(10);
  myQ.enqueue(3);
  var = myQ.rearElement();
  myQ.dequeue();
  myQ.enqueue(6);
  var = mQ.frontElement();
  System.out.println(var+" "+var);
 }
}