Question

Complete the following functions in the Queue.java/Queue.h files (ATTACHED BELOW):
a. void enqueue(int val)
b. int dequeue()
c. int getSize()

public class Queue {
  
private int maxQueueSize, front, rear, currentSize;
private int[] queue;
  
public Queue(int maxQueueSize) {
if (maxQueueSize <= 0)
System.out.println("Queue size should be a positive integer.");
else {
this.maxQueueSize = maxQueueSize;
front = rear = 0;
currentSize = 0;
queue = new int[maxQueueSize];
}
}
  
public void enqueue(int val) { // complete this function
}
  
public int dequeue() { // complete this function
}
  
public int getSize() {// complete this function
}
  
public String toString() {
if (getSize() == 0)
return "[]";
else {
String output = "[";
if (rear > front) {
for (int i = front; i < rear - 1; i++)
output += queue[i] + ", ";
output += queue[rear - 1] + "]";
} else {
for (int i = front; i < maxQueueSize - 1; i++)
output += queue[i] + ", ";
output += queue[maxQueueSize - 1];
  
for (int i = 0; i < rear; i++)
output += ", " + queue[i];
output += "]";
}
return output;
}
}
}

Answer 1

public class Queue {

   private int maxQueueSize, front, rear, currentSize;
   private int[] queue;

   public Queue(int maxQueueSize) {
       if (maxQueueSize <= 0)
           System.out.println("Queue size should be a positive integer.");
       else {
           this.maxQueueSize = maxQueueSize;
           front = rear = 0;
           currentSize = 0;
           queue = new int[maxQueueSize];
       }
   }

   public void enqueue(int val) { // complete this function
       // check queue is full or not
       if (maxQueueSize== rear) {
           System.out.printf("\nQueue is full\n");
           return;
       }

       // insert element at the rear
       else {
           queue[rear] = val;
           rear++;
       }
   }

   public int dequeue() { // complete this function
       // check for queue underflow
       if (front == rear) {
           System.out.println("UnderFlow\nProgram Terminated");
           System.exit(1);
       }

       int res = queue[front];

       front = (front + 1) % maxQueueSize;
       currentSize--;
       return res;
   }

   public int getSize() {// complete this function
       return rear;
   }

   public String toString() {
       if (getSize() == 0)
           return "[]";
       else {
           String output = "[";
           if (rear > front) {
               for (int i = front; i < rear - 1; i++)
                   output += queue[i] + ", ";
               output += queue[rear - 1] + "]";
           } else {
               for (int i = front; i < maxQueueSize - 1; i++)
                   output += queue[i] + ", ";
               output += queue[maxQueueSize - 1];

               for (int i = 0; i < rear; i++)
                   output += ", " + queue[i];
               output += "]";
           }
           return output;
       }
   }
}