题解 | #【模板】循环队列#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String s[] = in.nextLine().split(" ");
        int n = Integer.parseInt(s[0]);
        MyQueue q = new MyQueue(n+1);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            String str[] = in.nextLine().split(" ");
            if (str[0].equals("push")) {
                q.push(str[1]);
            }
            if (str[0].equals("pop")) {
                q.pop();
            }
            if (str[0].equals("front")) {
                q.front();
            }

        }
    }

}

class MyQueue {
    int front;
    int tail;
    int size;
    String [] nums;
    MyQueue(int size) {
        this.front = 0;
        this.tail = 0;
        this.size = size;
        nums = new String[size];
    }
    public void pop() {
        if (this.front == this.tail) {
            System.out.println("empty");
        } else {
            this.front = (this.front + 1) % this.size;
            System.out.println(nums[this.front]);
        }

    }
    public void push(String num) {
        if (this.front == (this.tail + 1) % this.size) {
            System.out.println("full");
        }else{
            this.tail = (this.tail + 1) % this.size;
            nums[this.tail] = num;
        }

    }

    public void front() {
        if (this.front == this.tail) {
            System.out.println("empty");
        } else {
            System.out.println(nums[(this.front + 1) % this.size]);
        }

    }

}