[데이터 구조] 대기 열의 세 가지 실현 방식

package dataStructure;

public class ArrayQueue {
	private int[] a;
	private int front;
	private int rear;
	private int size;//    
	private int items ;
	
	public ArrayQueue(int MaxSize) {
		size = MaxSize;
		a = new int[size];
		front = 0;
		rear = -1;
		items = 0;
	}
	
	boolean isEmpty() {
		return rear == -1;
	}
	
	boolean isFull() {
		return items == size;
	}
	
	int size() {
		return items;
	}
	void addQueue(int value) {
		if(isFull()) {
			System.out.println("  ！");
			return;
		}
		rear = ++rear % size;
		items++;
		a[rear] = value;
	}
	
	int delQueue() {
		if(isEmpty()) {
			System.out.println("  ！");
			return 0;
		}
		items--;
//		front = ++front % size;
//		return a[front];
		return a[front++ % size];	
	}
	
	int peek() {
		if(isEmpty()) {
			System.out.println("  ！");
			return 0;
		}
		return a[front];
	}
	
	int poll() {
		if(isEmpty()) {
			System.out.println("  ！");
			return 0;
		}
		return a[rear];
	}
	void dispaly() {
		if(isEmpty()) {
			System.out.println("  ！");
			return;
		}
		int item = front;
		for(int i = 0; i < size() ; i++) {
			System.out.print(a[item++ % size]+" ");
		}
		System.out.println();
	}
	public static void main(String[] args) {
		ArrayQueue aq = new ArrayQueue(5);
		aq.addQueue(1);
		aq.addQueue(2);
		aq.addQueue(6);
		aq.addQueue(5);
		aq.dispaly();
		aq.delQueue();
		aq.dispaly();
		System.out.println("    ：" + aq.size() + "     ： " + aq.size);
		System.out.println("    ：" + aq.peek());
		System.out.println("    ：" + aq.poll());
		
	}
}

package dataStructure;


public class DynArrayQueue {
	private int[] a;
	private int front;
	private int rear;
	private int size;//    
	private int items ;
	
	public DynArrayQueue(int MaxSize) {
		size = MaxSize;
		a = new int[size];
		front = 0;
		rear = -1;
		items = 0;
	}
	void doubleArray() {
		int[] newArray =new  int[2 * size];
		System.arraycopy(a, 0, newArray, 0, size);
		size = 2 * size;
		a = newArray;
	}
	boolean isEmpty() {
		return rear == -1;
	}
	
	boolean isFull() {
		return items == size;
	}
	
	int size() {
		return items;
	}
	void addQueue(int value) {
		if(isFull()) {
			doubleArray();
		}
		rear = ++rear % size;
		items++;
		a[rear] = value;
	}
	
	int delQueue() {
		if(isEmpty()) {
			System.out.println("  ！");
			return 0;
		}
		items--;
//		front = ++front % size;
//		return a[front];
		return a[front++ % size];	
	}
	
	int peek() {
		if(isEmpty()) {
			System.out.println("  ！");
			return 0;
		}
		return a[front];
	}
	
	int poll() {
		if(isEmpty()) {
			System.out.println("  ！");
			return 0;
		}
		return a[rear];
	}
	void dispaly() {
		if(isEmpty()) {
			System.out.println("  ！");
			return;
		}
		int item = front;
		for(int i = 0; i < size() ; i++) {
			System.out.print(a[item++ % size]+" ");
		}
		System.out.println();
	}
	public static void main(String[] args) {
		DynArrayQueue aq = new DynArrayQueue(2);
		aq.addQueue(1);
		aq.addQueue(2);
		aq.addQueue(6);
		aq.addQueue(5);
		aq.dispaly();
		aq.delQueue();
		aq.dispaly();
		System.out.println("    ：" + aq.size() + "      ：" + aq.size);
		System.out.println("    ：" + aq.peek());
		System.out.println("    ：" + aq.poll());
		
	}
}

package dataStructure;

class QueueNode<T> {
	private T data;
	private QueueNode<T> next = null;
	
	public QueueNode(T data) {
		this.data = data;
	}

	public T getData() {
		return data;
	}

	public void setData(T data) {
		this.data = data;
	}

	public QueueNode<T> getNext() {
		return next;
	}

	public void setNext(QueueNode<T> next) {
		this.next = next;
	}

	@Override
	public String toString() {
		return data + "->";
	}
	
}
public class LLQueue<T> {
	QueueNode<T> front;
	QueueNode<T> rear;
	
	public LLQueue() {
		front = rear = null;
	}
	
	int size() {
		int count = 0;
		QueueNode<T> cur = front;
		while(cur != null) {
			count++;
			cur = cur.getNext(); 
		}
		return count;
	}
	
	boolean isEmpty() {
		//return size() == 0;
		return front == null;
	}
	
	void addQueue(T data) {
		QueueNode<T> node = new QueueNode<>(data);
		if(isEmpty()) {
			rear = front = node;
		}else {
			rear.setNext(node);
			rear = node; 
		}
		
	}
	
	QueueNode<T> removeQueue() {
		if(isEmpty()) {
			System.out.println("  ！");
			return null;
		}
		if(front == rear)   
			return front = rear = null;
		QueueNode<T> del = front;
		front = front.getNext();
		return del;
	}
	
	QueueNode<T> peek(){
		return front;
	}
	
	QueueNode<T> poll(){
		return rear;
	}
	void display(){
		if(isEmpty()) {
			System.out.println("  ！");
			return;
		}
		QueueNode<T> cur = front;
		while(cur != null) {
			System.out.print(cur.getData() + "->");
			cur = cur.getNext();
		}
		System.out.println();
	}
	public static void main(String[] args) {
		LLQueue<Integer> lq = new LLQueue<>(); 
		lq.addQueue(2);
		lq.addQueue(5);
		lq.addQueue(7);
		lq.display();
		System.out.println("      ：" + lq.removeQueue());
		lq.display();
		System.out.println("    ：" + lq.size());
		System.out.println("    ：" + lq.peek());
		System.out.println("    ：" + lq.poll());	
	}
	
}