Saburo data structure algorithm study notes: array simulation circular queue
Circular queue: Meet the first-in-first-out characteristics of the queue , plus the conditional mandatory end-to-end connection.
It is worth noting that the end-to-end connection here is on the logical level, not on the physical level.
This time the array simulation circular queue is used instead of a linked list. Oh
Result display:
Refer to the complete source code:
/*
* author:sanalang
* time:2020.10.26
* function: CircleArrayQueue based on array
* */
import java.util.Scanner;
class CircleArrayQueueDemo {
public static void main(String[] args) {
//测试一把
System.out.println("测试数组模拟环形队列的案例~~~");
// 创建一个环形队列
CircleArray queue = new CircleArray(4); //说明设置 4, 其队列的有效数据最大是 3
char key = ' ';
// 接收用户输入
Scanner scanner = new Scanner(System.in);
boolean loop = true;
// 输出一个菜单
while (loop) {
System.out.println("s(show): 显示队列");
System.out.println("e(exit): 退出程序");
System.out.println("a(add): 添加数据到队列");
System.out.println("g(get): 从队列取出数据");
System.out.println("h(head): 查看队列头的数据");
key = scanner.next().charAt(0);// 接收一个字符
switch (key) {
case 's': queue.showQueue();
break;
case 'a':
System.out.println("输出一个数");
int value = scanner.nextInt();
queue.addQueue(value);
break;
case 'g':
// 取出数据
try {
int res = queue.getQueue(); System.out.printf("取出的数据是%d\n", res);
} catch (Exception e) {
// TODO: handle exception;
System.out.println(e.getMessage());
}
break;
case 'h': // 查看队列头的数据
try {
int res = queue.headQueue();
System.out.printf("队列头的数据是%d\n", res);
} catch (Exception e) {
// TODO:handle exception;
System.out.println(e.getMessage());
}
break;
case 'e': // 退出
scanner.close();
loop = false; break;
default:
break;
}
}
System.out.println("程序退出~~");
}
}
class CircleArray {
private int maxSize; // 表示数组的最大容量
//front 变量的含义做一个调整: front 就指向队列的第一个元素, 也就是说 arr[front] 就是队列的第一个元素
//front 的初始值 = 0
private int front;
//rear 变量的含义做一个调整:rear 指向队列的最后一个元素的后一个位置. 因为希望空出一个空间做为约定. //rear 的初始值 = 0
private int rear; // 队列尾
private int[] arr; // 该数据用于存放数据, 模拟队列
public CircleArray(int arrMaxSize) {
maxSize = arrMaxSize;
arr = new int[maxSize];
}
// 判断队列是否满
public boolean isFull() {
return (rear + 1) % maxSize == front;
}
public boolean isEmpty() {
return rear == front;
}
public void addQueue(int n) { // 判断队列是否满
if (isFull()) { System.out.println("队列满,不能加入数据~"); return;
}
//直接将数据加入
arr[rear] = n;
//将 rear 后移, 这里必须考虑取模
rear = (rear + 1) % maxSize;
}
// 获取队列的数据, 出队列
public int getQueue() {
// 判断队列是否空
if (isEmpty()) {
// 通过抛出异常
throw new RuntimeException("队列空,不能取数据");
}
int value = arr[front];
front = (front + 1) % maxSize; return value;
}
// 显示队列的所有数据
public void showQueue() {
// 遍历
if (isEmpty()) { System.out.println("队列空的,没有数据~~"); return;
}
for (int i = front; i < front + size() ; i++)
{ System.out.printf("arr[%d]=%d\n", i % maxSize, arr[i % maxSize]);
}
}
// 求出当前队列有效数据的个数
public int size() {
rear = 2;
front = 1;
maxSize = 3;
return (rear + maxSize - front) % maxSize;
}
// 显示队列的头数据, 注意不是取出数据
public int headQueue() {
// 判断
if (isEmpty()) {
throw new RuntimeException("队列空的,没有数据~~");
}
return arr[front];
}
}
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Array Simulation Queue System