题目描述
实现一种猫狗队列 可以add,pollAll,pollDog,pollCat,isEmpty,isDogEmpty,isCatEmpty 要求如下：
用户可以调用add方法将cat类或者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和cat的实例；用户可以调用isDogEmpty方法，检查队列中是否还有do的实例；用户可以调用isCatEmpty方法，检查队列中是否还有cat的实例。
解题思路
构建猫和狗两个队列，设计一个类PetEnterQueue ，用于记录放入队列的每个元素的时间戳，取出时按时间戳来判断从dog队列或cat队列取出元素
代码
package TestNode
.StackAndQueue
;
import java
.util
.LinkedList
;
import java
.util
.Queue
;
public class CatDogQueue {
public static class Pet{
private String type
;
public Pet(String type
){
this.type
= type
;
}
public String
getType() {
return type
;
}
}
public static class Cat extends Pet{
public Cat(){
super("Cat");
}
}
public static class Dog extends Pet{
public Dog(){
super("Dog");
}
}
public static class PetEnterQueue{
private Pet pet
;
private long count
;
public PetEnterQueue(Pet pet
, long count
){
this.pet
= pet
;
this.count
= count
;
}
public long getCount() {
return count
;
}
public Pet
getPet() {
return pet
;
}
public String
getEnterPetType(){
return pet
.getType();
}
}
private Queue
<PetEnterQueue> dogQueue
;
private Queue
<PetEnterQueue> catQueue
;
private long count
;
public CatDogQueue(){
dogQueue
= new LinkedList<>();
catQueue
= new LinkedList<>();
count
= 0;
}
public void add(Pet pet
){
if (pet
.getType().equals("Dog")){
this.dogQueue
.add(new PetEnterQueue(pet
, count
++));
}else if (pet
.getType().equals("Cat")){
this.catQueue
.add(new PetEnterQueue(pet
, count
++));
}else {
throw new RuntimeException("err, not dog or cat");
}
}
public Pet
pollAll(){
if (!this.dogQueue
.isEmpty() && !this.catQueue
.isEmpty()){
if (this.dogQueue
.peek().getCount() < this.catQueue
.peek().getCount()){
return this.dogQueue
.poll().getPet();
}else {
return this.catQueue
.poll().getPet();
}
}else if (!this.dogQueue
.isEmpty()){
return dogQueue
.poll().getPet();
}else if (!this.dogQueue
.isEmpty()){
return this.catQueue
.poll().getPet();
}else {
throw new RuntimeException("err, queue is empty");
}
}
public Dog
pollDog() {
if (!isDogEmpty()) {
return (Dog
) this.dogQueue
.poll().getPet();
} else {
throw new RuntimeException("err,dog queue is empty");
}
}
public Cat
pollCat() {
if (!isCatEmpty()) {
return (Cat
) this.catQueue
.poll().getPet();
} else {
throw new RuntimeException("err,cat queue is empty");
}
}
public boolean isEmpty() {
return this.dogQueue
.isEmpty() && this.catQueue
.isEmpty();
}
public boolean isDogEmpty() {
return this.dogQueue
.isEmpty();
}
public boolean isCatEmpty() {
return this.catQueue
.isEmpty();
}
}
