#2.已知字符串st="dffsda123dfsadfa",判断每个单词出现的次数
st="dffsda123dfsadfa"
list1=[]
list2=[]
for i in st:
    list1.append(i)
    if i not in list2:
        list2.append(i)
for i in list2:
    print(i,"出现的次数为",list1.count(i),"次")

运行结果：