题解#Head and Tail of the Queue#

import java.util.ArrayDeque;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        ArrayDeque deque = new ArrayDeque();

        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String name = scanner.next();
            // 初始化队列中的数据
            deque.offerLast(name);
        }

        // write your code here......
        Boolean flag = true; //表示奇偶，奇偶出队分别是首尾
        while (!deque.isEmpty()) { //队列没有人为止
            if (flag) { //弹队首
                System.out.println(deque.getFirst());
                deque.removeFirst();
                flag = false; //交替
            } else { //弹队尾
                System.out.println(deque.getLast());
                deque.removeLast();
                flag = true; //交替
            }
        }



    }

}