循环队列（思路+代码）_循环队列代码

变量：

头指针：front

尾指针：rear

最大长度：maxSize

数组队列：arr[]

思路：

front指向第一个有效数据

rear指向最后一个位置的下一个位置

 

公式：

是否为满：

（rear + 1）%maxSize == front

是否为空

rear == front

打印

print（arr【i】 % maxSize）

入队、出队

front = (front + 1) % maxSize;

rear = (rear + 1) % maxSize;

package sparseArr;
 
import java.util.Scanner;
 
 
public class SparseArray {
	public static void main(String[] args) {
		Query q = new Query(4);
		char k = ' ';
		Scanner sc = new Scanner(System.in);
		boolean loop = true;
		while(loop) {
			System.out.println("s(Show)");
			System.out.println("e(exit)");
			System.out.println("a(add)");
			System.out.println("g(get)");
			System.out.println("h(head)");
			k = sc.next().charAt(0);
			switch(k) {
				case 's':
					q.print();
					break;
				case 'e':
					sc.close();
					loop = false;
					break;
				case 'a':
					System.out.print("输入一个数：");
					int n = sc.nextInt();
					q.push(n);
					break;
				case 'g':
					int res = q.pop();
					System.out.println("取出的数据是：" + res);
					break;
				case 'h':
					int res1 = q.headQueue();
					System.out.println("头数据："+res1);
					break;
			}
		}
	}
}
class Query{
	private int maxSize;
	private int rear;
	private int front;
	private int[] arr;
	
	public Query(int maxSize) {
		this.maxSize = maxSize;
		rear = 0;
		front = 0;
		arr = new int[maxSize];
	}
	public int headQueue() {
		if(isEmpty()) {
			System.out.print("队列为空");
			return -1;
		}
		return arr[front];
	}
	
	public boolean isFull() {
		return (rear + 1) % maxSize == front;
	}
	public boolean isEmpty() {
		return rear == front;
	}
	public void push(int val) {
		if(isFull()) {
			System.out.println("队列为满！");
			return;
		}
		arr[rear] = val;
		rear = (rear + 1) % maxSize;
	}
	public int pop() {
		if(isEmpty()) {
			System.out.println("队列为空！");
			return -1;
		}
		int val = arr[front];
		front = (front + 1) % maxSize;
		return val;
	}
	public void print() {
		if(isEmpty()) {
			System.out.println("队列为空！");
		}
		for(int i = front; i <= usefulVal();i++) {
			System.out.printf("arr[%d] = %d\n",i % maxSize,arr[i % maxSize]);
		}
	}
	public int usefulVal() {
		return (rear + maxSize - front) % maxSize;
	}
	public int peak() {
		if(isEmpty()) {
			System.out.println("队列为空！");
			return -1;
		}
		int val = arr[(front+1)%maxSize];
		return val;
	}
}