题解 | #字符统计#

用一个字典存字符出现的次数，键为出现次数，值为字母。同一出现次数的字母将被拼接在同一键的同一值下。

while 1:
    try:
        s=input()
        dic={}
        for le in set(s):
            n=0
            for i in s:
                n+=int(le==i)
            if n in dic:
                dic[n]+=le
            else:
                dic[n]=le
        n_list=sorted(list(dic.keys()),reverse=True)
        an=''
        for i in n_list:
            temp=''.join(sorted(dic[i]))
            an+=temp
        print(an)
    except:
        break