[백준] 2910 빈도 정렬 - Data Structure / Java

• 문제 링크

2910번: 빈도 정렬

 

• 풀이 과정

 

• 풀이 코드

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

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));
        StringTokenizer st = new StringTokenizer(br.readLine());

        int n = Integer.parseInt(st.nextToken());

        Map<Integer, Integer> map = new LinkedHashMap<>();

        st = new StringTokenizer(br.readLine());
        while (n-- > 0) {
            int input = Integer.parseInt(st.nextToken());
            map.put(input, map.getOrDefault(input, 0) + 1);
        }

        List<Integer> list = new ArrayList<>(map.keySet());

        Collections.sort(list, new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                return map.get(o2) - map.get(o1);
            }
        });

        for (int i : list) {
            int cnt = map.get(i);
            while (cnt-- > 0)
                bw.write(i + " ");
        }

        bw.flush();
    }

}