题解 | #【模板】循环队列#

import java.util.*;

// 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);
        // 注意 hasNext 和 hasNextLine 的区别
        String a = in.nextLine();
        String [] as = a.split(" ");
        int maxsize = Integer.parseInt(as[0]);
        Queue que = new LinkedList();
        while (in.hasNextLine()) {
            String str = in.nextLine();
            String[] strs = str.split(" ");
            if ("push".equals(strs[0]) && maxsize > que.size()) {
                que.offer(strs[1]);
            }else if("push".equals(strs[0]) && maxsize <=  que.size()){
                    System.out.println("full");
            } else if ("pop".equals(strs[0])) {
                if (que.size() > 0) {
                    System.out.println(que.poll());
                } else {
                    System.out.println("empty");
                }
            } else if ("front".equals(strs[0])) {
                if (que.size() > 0) {
                    System.out.println(que.peek());
                } else {
                    System.out.println("empty");
                }
            }
        }
    }
}