Q3_7.java

import java.util.LinkedList;

public class Q3_7{
	public static void main(String[] args){
		Dog[] dogs = {new Dog("doga"),new Dog("dogb"),new Dog("dogc"),new Dog("dogd"),new Dog("doge")};
		Cat[] cats = {new Cat("cata"),new Cat("catb"),new Cat("catc")};
		AnimalShelter ash = new AnimalShelter();
		ash.enqueue(dogs[0]);
		ash.enqueue(dogs[1]);
		System.out.println(ash.dequeueDog().name);
		ash.enqueue(cats[0]);
		System.out.println(ash.dequeueAny().name);			
		System.out.println(ash.dequeueAny().name);	
		ash.enqueue(dogs[2]);
		ash.enqueue(cats[1]);
		ash.enqueue(cats[2]);
		ash.enqueue(dogs[3]);
		ash.enqueue(dogs[4]);
		
		System.out.println(ash.size());
		for(int i = 0; i< 5;i++){
			System.out.println(ash.dequeueAny().name);
		}
		
	}	
}
class AnimalShelter{
	
	LinkedList<Dog> dogs;
	LinkedList<Cat> cats;
	int order;
	
	AnimalShelter(){
		dogs = new LinkedList<Dog>();
		cats = new LinkedList<Cat>();
		order = 1;
	}
	
	void enqueue(Animal animal){
		if(animal.getClass()== Cat.class){
			Cat c = (Cat)animal;
			c.setOrder(order);
			cats.add(c);
			order++;
			
		}
		else if(animal.getClass()== Dog.class){
			Dog d = (Dog)animal;
			d.setOrder(order);
			dogs.add(d);
			order++;
		}
	}
	Animal dequeueAny(){
		if(dogs.isEmpty()&& cats.isEmpty())
			return null;
		if(!dogs.isEmpty()&& !cats.isEmpty()){
			Dog d = dogs.getFirst();
			Cat c = cats.getFirst();
			return d.getOrder()<c.getOrder() ? dogs.removeFirst():cats.removeFirst();
		}
		else return dogs.isEmpty()? cats.removeFirst():dogs.removeFirst();
		
	}
	Dog dequeueDog(){
		if(dogs.isEmpty())
			return null;
		else
			return dogs.removeFirst();
	}
	Cat dequeueCat(){
		if(cats.isEmpty())
			return null;
		else
			return cats.removeFirst();
	}
	int size(){
		return cats.size()+dogs.size();
	}
}
abstract class  Animal{
	String name;
	int order;
	
	Animal(String n){
		name = n;
	}
	void setOrder(int o){
		this.order = o;
	}
	
	int getOrder(){
		return order;
	}
}
class Dog extends Animal{
	Dog(String s){
		super(s);
	}		
}
class Cat extends Animal{
	Cat(String s){
		super(s);
	}
}