str_a=input() str_a_new=list(set(str_a)) str_a_new.sort(key=lambda x:(str_a.count(x),str_a.index(x))) #对这个列表排序,先根据出现次数统计排序,若统计次数相同则根据出现的索引排序 # print(str_a_new) for i in str_a_new: if str_a.count(i)==1: &n...