[백준 10845 / Java] 큐

문제 링크

https://www.acmicpc.net/problem/10845

10845번: 큐

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풀이

큐 포스팅 링크

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

public class Main {

    static List<Integer> queue = new ArrayList<>();
    static StringBuffer sb = new StringBuffer();

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st;

        int N = Integer.parseInt(br.readLine());

        for(int i = 0; i < N; i++){
            st = new StringTokenizer(br.readLine(), " ");

            switch(st.nextToken()){
                case "push": push(Integer.parseInt(st.nextToken()));
                    break;
                case "pop" : pop();
                    break;
                case "size" : size();
                    break;
                case "empty" : empty();
                    break;
                case "front" : front();
                    break;
                case "back" : back();
                    break;
            }
        }
        System.out.println(sb.toString());
    }

    private static void push(int i) {
        queue.add(i);
    }

    private static void pop() {
        if(queue.isEmpty()) sb.append(-1 + "\n");
        else{
            sb.append(queue.remove(0) + "\n");
        }
    }

    private static void size() {
        sb.append(queue.size() + "\n");
    }

    private static void empty() {
        if(queue.isEmpty()) sb.append(1 + "\n");
        else sb.append(0 + "\n");
    }

    private static void front() {
        if(queue.isEmpty()) sb.append(-1 + "\n");
        else{
            sb.append(queue.get(0) + "\n");
        }
    }

    private static void back() {
        if(queue.isEmpty()) sb.append(-1 + "\n");
        else{
            sb.append(queue.get(queue.size() - 1) + "\n");
        }
    }

}