题解 | #HJ102 字符统计#

import java.util.*;

/**
 * HJ102 字符统计 - 简单
 */
public class HJ102 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            String str = sc.nextLine();
            TreeMap<Character, Integer> map = new TreeMap<>();
            for (int i = 0; i < str.length(); i++) {
                char c = str.charAt(i);
                map.put(c, map.getOrDefault(c, 0) + 1);
            }
            List<Map.Entry> list = new ArrayList<>(map.entrySet());
            Collections.sort(list, (o1, o2) -> (int) o2.getValue() - (int) o1.getValue());
            for (Map.Entry entry : list) {
                System.out.print(entry.getKey());
            }
            System.out.println();
        }
        sc.close();
    }
}