数据结构-08 队列(循环队列)

/**
* 添加数据，从队尾插入
*/
public void insert(long value){
//当end指到队列结尾时，再调整指到初始位置
if(end == arr.length - 1){
end = -1;
}
arr[++end] = value;
elements++;
}

/**
* 删除数据，从队头删除
*/
public long remove(){
long value = arr[front++];
//当front指到队列结尾时，再调整指到初始位置
if(front == arr.length){
front = 0;
}
elements--;
return value;
}

package org.gzw.ch03;
/**
* 队列
*/
public class MyCycleQueue {
//底层试用数组
private long[] arr;
//有效数据的长度
private int elements;
//对头
private int front;
//队尾
private int end;

/**
* 默认无参构造
*/
public MyCycleQueue(){
arr = new long[10];
elements = 0;
front = 0;
end = -1;
}

/**
* 带参数的构造方法
*/
public MyCycleQueue(int maxsize){
arr = new long[maxsize];
elements = 0;
front = 0;
end = -1;
}

/**
* 添加数据，从队尾插入
*/
public void insert(long value){
//当end指到队列结尾时，再调整指到初始位置
if(end == arr.length - 1){
end = -1;
}
arr[++end] = value;
elements++;
}

/**
* 删除数据，从队头删除
*/
public long remove(){
long value = arr[front++];
//当front指到队列结尾时，再调整指到初始位置
if(front == arr.length){
front = 0;
}
elements--;
return value;
}

/**
* 查看数据，从队头查看
*/
public long peek(){
return arr[front];
}

/**
* 判断是否为空
*/
public boolean isEmpty(){
return elements == 0;
}

/**
* 判断是否满了
*/
public boolean isFull(){
//return (end - front) == arr.length;
return elements == arr.length;
}
}

package org.gzw.ch03;

public class TestMyCycleQueue {

public static void main(String[] args) {
MyCycleQueue myCycleQueue = new MyCycleQueue(4);
myCycleQueue.insert(23);
myCycleQueue.insert(45);
myCycleQueue.insert(13);
myCycleQueue.insert(1);

System.out.println(myCycleQueue.isEmpty());
System.out.println(myCycleQueue.isFull());
System.out.println(myCycleQueue.peek());
System.out.println(myCycleQueue.peek());

while(!myCycleQueue.isEmpty()){
System.out.print(myCycleQueue.remove() + ", ");
}
System.out.println();
System.out.println(myCycleQueue.isFull());
System.out.println(myCycleQueue.isEmpty());
System.out.println(myCycleQueue.peek());

System.out.println("-----------------------------");

//这里不会报错，原因是end位置在队列结尾时，会在指向初始位置
myCycleQueue.insert(21);
System.out.println(myCycleQueue.peek());
myCycleQueue.insert(22);
myCycleQueue.insert(23);
myCycleQueue.insert(24);

while(!myCycleQueue.isEmpty()){
System.out.print(myCycleQueue.remove() + ", ");
}

System.out.println();
System.out.println(myCycleQueue.peek());
}

}

false
true
23
23
23, 45, 13, 1,
false
true
23
-----------------------------
21
21, 22, 23, 24,
21