【数据结构笔记】循环队列——Java实现

1. 入队： rear = (rear + 1) % m
2. 出队： front = (front + 1) % m
3. 队空： front = rear
4. 队满： front = (rear + 1) % m
5. 当前队列中的元素数目： n = (rear - front + m) % m

图及公式源于：https://blog.youkuaiyun.com/u011080472/article/details/51173584

 

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Java代码实现：

public class Queue {
	private int[] array;
	private int front;
	private int rear;

	public Queue(int capacity) {
		this.array = new int[capacity];
	}

	/**
	 * 入队
	 * 
	 * @throws Exception
	 */
	public void inQueue(int element) throws Exception {
		if ((rear + 1) % array.length == front) {
			throw new Exception();
		}

		array[rear] = element;
		rear = (rear + 1) % array.length;
	}

	/**
	 * 出队
	 * 
	 * @throws Exception
	 */
	public int outQueue() throws Exception {
		if (rear == front) {
			throw new Exception();
		}
		int outQueueElement = array[front];
		front = (front + 1) % array.length;
		return outQueueElement;
	}

	/**
	 * 输出队列
	 */
	public void output() {
		for (int i = front; i != rear; i = (i + 1) % array.length) {
			System.out.println(array[i]);
		}
	}

	public static void main(String[] args) throws Exception {
		Queue queue = new Queue(6);
		queue.inQueue(9);
		queue.inQueue(5);
		queue.inQueue(7);
		queue.inQueue(8);
		queue.inQueue(1);
		queue.outQueue();
		queue.outQueue();
		queue.outQueue();
		queue.inQueue(2);
		queue.inQueue(5);
		queue.inQueue(3);
		queue.output();
	}
}