큐, 덱(10845, 2164)

[큐 _ 10845]

 

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Problem_10845 {

    public static void main(String[] args) {
        Queue<Integer> queue = new LinkedList<>();

        Scanner scanner = new Scanner(System.in);
        int operationNum = scanner.nextInt();

        for(int i=0; i<operationNum; ++i){
            String input = scanner.next();

            switch (input){
                case "push":
                    int num = scanner.nextInt();
                    queue.offer(num);
                    break;

                case "pop":
                    System.out.println(queue.isEmpty() ? -1 : queue.poll());
                    break;

                case "size":
                    System.out.println(queue.size());
                    break;

                case "empty":
                    System.out.println(queue.isEmpty() ? 1 : 0);
                    break;

                case "front":
                    System.out.println(queue.isEmpty() ? -1 : queue.peek());
                    break;

                case "back":
                    if(queue.isEmpty()) System.out.println(-1);
                    else {
                        int lastNum = ((LinkedList<Integer>) queue).getLast();
                        System.out.println(lastNum);
                    }

                    break;
            }
        }
    }
}

 

[카드2 _ 2164]

 

 

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Problem_2164 {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int N = scanner.nextInt();
        Queue<Integer> queue = new LinkedList<>();

        for(int i=1; i<=N; ++i)
            queue.offer(i);

        while (queue.size() > 1){
            //맨 앞을 pop
            queue.poll();

            //맨 앞의 숫자를 맨 뒤로 보내기
            int frontNum = queue.poll();
            queue.offer(frontNum);
        }

        System.out.println(queue.poll());
    }
}