BOJ 7785 회사에 있는 사람

https://www.acmicpc.net/problem/7785

7785번: 회사에 있는 사람

 

 

import java.io.*;
import java.util.*;
public class Main
{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		
		int n = Integer.parseInt(br.readLine());
		
		HashMap<String,Boolean> record = new HashMap();
		
		for(int i=0; i<n; i++){
		    String[] temp = br.readLine().split(" ");
		    if(temp[1].equals("enter")){
		        record.put(temp[0],true);
		    }else{
		        record.put(temp[0],false);
		    }
		}
		List<String> names = new ArrayList<>();
		for(String name : record.keySet()){
		    if(record.get(name)){
		        names.add(name);
		    }
		}
		Collections.sort(names, Collections.reverseOrder());
		
		for(String s : names){
		    bw.write(s+"\n");
		}
		bw.flush();
	}
}

 

 

Set 을 이용

import java.util.*;

class Main
{
    public static void main (String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        Set<String> entered = new TreeSet<>();
        for (int i = 0; i < N; i++) {
            String name = sc.next();
            String status = sc.next();
            if (status.equals("enter"))
                entered.add(name);
            else entered.remove(name);
        }

        String[] orderedAnswer = entered.toArray(new String[entered.size()]);
        for (int i = orderedAnswer.length - 1; i >= 0; i--)
            System.out.println(orderedAnswer[i]);
    }
}

 

 

정렬을 이용

 

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

class Main
{
    public static void main (String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        String[][] records = new String[N][2];
        for (int i = 0; i < N; i++) {
            records[i][0] = sc.next();
            records[i][1] = sc.next();
        }

        Arrays.sort(records, new Comparator<String[]>() {
            @Override
            public int compare(String[] o1, String[] o2) {
                return o2[0].compareTo(o1[0]);
            }
        });

        for (int i = 0; i < N - 1; i++) {
            if (records[i][1].equals("enter") && !records[i][0].equals(records[i + 1][0]))
                System.out.println(records[i][0]);
        }
        if (records[N - 1][1].equals("enter"))
            System.out.println(records[N - 1][0]);
    }
}