백준 10845번 - 큐 (Java 8)

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

10845번: 큐

아무 생각 없이 LinkedList 사용

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.StringTokenizer;

public class Main {
    static LinkedList<Integer> queue = new LinkedList();
    static StringTokenizer st;
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int numOfCase = Integer.parseInt(br.readLine());
        for(int i=0; i<numOfCase; i++){
            st = new StringTokenizer(br.readLine());
            readCommand(st.nextToken());
        }
    }
    public static void readCommand(String input){
        if (input.equals("push")) {
            int X = Integer.parseInt(st.nextToken());
            push(X);
        }
        if (input.equals("pop")) {
            pop();
        }
        if (input.equals("size")) {
            size();
        }
        if (input.equals("empty")) {
            empty();
        }
        if (input.equals("front")) {
            front();
        }
        if (input.equals("back")) {
            back();
        }
    }
    public static void push(int X){
        queue.add(X);
    }
    public static void pop(){
        if(queue.size() == 0){
            System.out.println(-1);
        } else{
            System.out.println(queue.get(0));
            queue.remove(queue.get(0));
        }
    }
    public static void size(){
        System.out.println(queue.size());
    }
    public static void empty(){
        if(queue.size() == 0){
            System.out.println(1);
        } else{
            System.out.println(0);
        }
    }
    public static void front(){
        if(queue.size() == 0){
            System.out.println(-1);
        } else{
            System.out.println(queue.get(0));
        }
    }
    public static void back(){
        if(queue.size() == 0){
            System.out.println(-1);
        } else{
            System.out.println(queue.get(queue.size()-1));
        }
    }
}

 

큐 사용

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;

public class Main {
    static Queue<Integer> queue = new LinkedList<>();
    static StringTokenizer st;
    static int X;
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int numOfCase = Integer.parseInt(br.readLine());
        for(int i=0; i<numOfCase; i++){
            st = new StringTokenizer(br.readLine());
            readCommand(st.nextToken());
        }
    }
    public static void readCommand(String input){
        if (input.equals("push")) {
            X = Integer.parseInt(st.nextToken());
            push(X);
        }
        if (input.equals("pop")) {
            pop();
        }
        if (input.equals("size")) {
            size();
        }
        if (input.equals("empty")) {
            empty();
        }
        if (input.equals("front")) {
            front();
        }
        if (input.equals("back")) {
            back();
        }
    }
    public static void push(int X){
        queue.offer(X);
    }
    public static void pop(){
        if(queue.size() == 0){
            System.out.println(-1);
        } else{
            System.out.println(queue.poll());
        }
    }
    public static void size(){
        System.out.println(queue.size());
    }
    public static void empty(){
        if(queue.size() == 0){
            System.out.println(1);
        } else{
            System.out.println(0);
        }
    }
    public static void front(){
        if(queue.size() == 0){
            System.out.println(-1);
        } else{
            System.out.println(queue.peek());
        }
    }
    public static void back(){
        if(queue.size() == 0){
            System.out.println(-1);
        } else{
            System.out.println(X);
        }
    }
}

 

언젠가 대량 리팩토링을 해야할 것 같다.