程序员代码面试指南--猫狗队列

/**
	猫狗队列
	【题目】
	实现一种狗猫队列的结构,要求如下:
	用户可以调用add方法将cat类或dog类的实例放入队列中;
	用户可以调用pollAll方法,将队列中所有的实例按照进队列的先后顺序依次弹出;
	用户可以调用pollDog方法,将队列中dog类的实例按照进队列的先后顺序依次弹出;
	用户可以调用pollCat方法,将队列中cat类的实例按照进队列的先后顺序依次弹出;
	用户可以调用isEmpty方法,检查队列中是否还有dog或cat的实例;
	用户可以调用isDogEmpty方法,检查队列中是否有dog类的实例;
	用户可以调用isCatEmpty方法,检查队列中是否有cat类的实例。
 */
import java.util.LinkedList;
import java.util.Queue;
public class C04_DogCatQueue {
	public static void main(String[] args) {
		DogCatQ test = new DogCatQ();

		Pet dog1 = new Dog();
		Pet cat1 = new Cat();
		Pet dog2 = new Dog();
		Pet cat2 = new Cat();
		Pet dog3 = new Dog();
		Pet cat3 = new Cat();

		test.add(dog1);
		test.add(cat1);
		test.add(dog2);
		test.add(cat2);
		test.add(dog3);
		test.add(cat3);

		test.add(dog1);
		test.add(cat1);
		test.add(dog2);
		test.add(cat2);
		test.add(dog3);
		test.add(cat3);
		
		// test.pollAll();
		// System.out.println(test.isEmpty());
		while (!test.isDogQueueEmpty()) {
			System.out.println(test.pollDog().getPetType());
		}
	}
	///////////////////题目给定的三个类///////////////////////////
	public static class Pet {
		private String type;

		public Pet(String type) {
			this.type = type;
		}

		public String getPetType() {//类型
			return this.type;
		}
	}

	public static class Dog extends Pet {
		public Dog() {
			super("dog");
		}
	}

	public static class Cat extends Pet {
		public Cat() {
			super("cat");
		}
	}
	///////////////////我的队列////////////////////////////
	public static class petEnterQueue{
		private Pet pet;
		private int count;
		public petEnterQueue(Pet pet,int count) {
			this.pet = pet;
			this.count = count;
		}
		public Pet getPet() {
			return pet;
		}
		public int getCount() {
			return count;
		}
		public String getPetType(){
			return pet.getPetType();
		}
	}
	public static class DogCatQ{
		private Queue<petEnterQueue> dogQ;
		private Queue<petEnterQueue> catQ;
		private int count;
		public DogCatQ(){
			this.dogQ = new LinkedList<petEnterQueue>();
			this.catQ = new LinkedList<petEnterQueue>();
			this.count = 0;
		}
		//添加进队列
		public void add(Pet pet){
			if(pet.getPetType().equals("dog")){
				dogQ.add(new petEnterQueue(pet, count++));
			}else if(pet.getPetType().equals("cat")){
				catQ.add(new petEnterQueue(pet, count++));
			} else {
				throw new RuntimeException("type erroe,not dog or cat");
			}
		}
		public void pollAll(){
			while(!isEmpty()){
				if(!dogQ.isEmpty() && !catQ.isEmpty()){
					//猫狗队列都不为空的时候
					if(dogQ.peek().getCount()>catQ.peek().getCount()){
						 dogQ.poll();
					}else {
						 catQ.poll();
					}
				}else if(!dogQ.isEmpty()){
					 dogQ.poll();
				}else if(!catQ.isEmpty()){
					 catQ.poll();
				}
			}
		}
		public Dog pollDog() {
			if(!isDogQueueEmpty()){
				return (Dog) dogQ.poll().getPet();
			}
			throw new RuntimeException("Dog queue is empty!");
		}

		public Cat pollCat() {
			if(!isCatQueueEmpty()){
				return (Cat) catQ.peek().getPet();
			}
			throw new RuntimeException("Cat queue is empty!");
		}

		public boolean isEmpty() {//队列是否为空
			return catQ.isEmpty() && dogQ.isEmpty();
		}

		public boolean isDogQueueEmpty() {
			return dogQ.isEmpty();
		}

		public boolean isCatQueueEmpty() {
			return catQ.isEmpty();
		}

	}
}