[백준] 21944 문제 추천 시스템 Version 2 - Java

 

 

지난번에 풀었던 버전1 문제와 비슷하지만.. 추가된 조건들이 많아 구현하는데 어려움이 있었다..

 

알고리즘에 대한 분류는 전체 알고리즘의 수가 100개임을 고려해 ArrayList를 이용해 각각 추가해서 처리해줬고, 알고리즘이 추가됨에 따라 해시맵으로는 문제 번호를 통해 알고리즘 분류와 난이도를 얻을 수 있도록 설계했다.

 

풀다 보니 코드가 길어져서.. 중간에 실수가 있었으면 정말 슬펐을 것 같다..

 

import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();

        TreeSet<Problem> ts = new TreeSet<>();
        HashMap<Integer, Problem2> hm = new HashMap<>();

        ArrayList<TreeSet<Problem>> algorithm_list = new ArrayList<>();

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

        StringTokenizer st;

        for(int i=0; i<101; i++){
            algorithm_list.add(new TreeSet<>()); 
        } // algorithm's kind == 100

        for(int i=0; i<N; i++){     
            st = new StringTokenizer(br.readLine());       
            int num = Integer.parseInt(st.nextToken());            
            int difficulty = Integer.parseInt(st.nextToken());    
            int algorithm = Integer.parseInt(st.nextToken());            
            
            ts.add(new Problem(num, difficulty));
            algorithm_list.get(algorithm).add(new Problem(num, difficulty));
            hm.put(num, new Problem2(difficulty, algorithm));
        }

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

        for(int i=0; i<M; i++){
            st = new StringTokenizer(br.readLine());
            String command = st.nextToken();

            if(command.equals("recommend")){
                int algorithm = Integer.parseInt(st.nextToken());
                int cmd = Integer.parseInt(st.nextToken());

                if(cmd == 1){
                    sb.append(algorithm_list.get(algorithm).last().num + "\n"); // first 일수도..
                }
                if(cmd == -1){
                    sb.append(algorithm_list.get(algorithm).first().num + "\n"); // last 일수도..
                }
            }

            if(command.equals("recommend2")){
                int cmd = Integer.parseInt(st.nextToken());

                if(cmd == 1){
                    sb.append(ts.last().num + "\n"); // swap..?
                }
                if(cmd == -1){
                    sb.append(ts.first().num + "\n"); // swap?
                }
            }

            if(command.equals("recommend3")){
                int cmd = Integer.parseInt(st.nextToken());
                int condition = Integer.parseInt(st.nextToken());

                if(cmd == 1){
                    Problem temp = ts.higher(new Problem(0, condition));
                    if(temp == null){
                        sb.append(-1 + "\n");
                    }else{
                        sb.append(temp.num + "\n");
                    }
                }

                if(cmd == -1){
                    Problem temp = ts.lower(new Problem(0, condition));
                    if(temp == null){
                        sb.append(-1 + "\n");
                    }else{
                        sb.append(temp.num + "\n");
                    }
                }
            }

            if(command.equals("add")){
                int num = Integer.parseInt(st.nextToken());
                int difficulty = Integer.parseInt(st.nextToken());
                int algorithm = Integer.parseInt(st.nextToken());

                ts.add(new Problem(num, difficulty));
                algorithm_list.get(algorithm).add(new Problem(num, difficulty));
                hm.put(num, new Problem2(difficulty, algorithm));                
            }

            if(command.equals("solved")){
                int num = Integer.parseInt(st.nextToken());
                int difficulty = hm.get(num).difficulty;
                int algorithm = hm.get(num).algorithm;

                ts.remove(new Problem(num, difficulty));
                hm.remove(num);
                algorithm_list.get(algorithm).remove(new Problem(num, difficulty));
                
            }
        }

        System.out.println(sb);

        

    }

    static class Problem implements Comparable<Problem>{
        int num = 0;
        int difficulty = 0;

        Problem(int a, int b){
            num = a;
            difficulty = b;
        }

        public int compareTo(Problem o2){
            if(difficulty > o2.difficulty){
                return 1;                
            }else if(difficulty < o2.difficulty){
                return -1;
            }else{
                if(num > o2.num){
                    return 1;
                }else if(num < o2.num){
                    return -1;
                }else{
                    return 0;
                }
            }
        }

    }// end of Problem

    static class Problem2{
        int difficulty = 0;
        int algorithm = 0;

        Problem2(int a, int b){
            difficulty = a;
            algorithm = b;
        }
    }

}