题解 | #字符统计#

TreeMap存放，自动按ASCII码排序

import java.util.Scanner;
import java.util.TreeMap;

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

        //将字符存入TreeMap
        TreeMap<Character,Integer> map = new TreeMap<>();
        for (int i = 0; i < str.length(); i++) {
            if(!map.containsKey(str.charAt(i))){
                map.put(str.charAt(i),1);
            }else{
                map.put(str.charAt(i),map.get(str.charAt(i))+1);
            }
        }

        //找到max值
        int max = 0;
        for (int val:map.values()) {
            if(val>max)
                max = val;
        }

        //输出
        while (max>0){
            for (char key:map.keySet()){
                if(map.get(key)==max)
                    System.out.print(key);
            }
            max--;
        }

    }
}