第一个问题是，当你要求用户输入时，你会得到一个字符串，所以，如果你输入如下内容：Monday Tuesday hotdog，那么days变量将如下所示：
"Monday Tuesday hotdog"
所以，正如你所说，你不关心输入是什么，只要你能得到多少天，这意味着一个数字，因此，你想得到字符串的长度，或者换句话说，字符串中有多少个单词，你可以简单地得到如下：

len(days.split())

那么，现在你有多少天。你所要做的就是简单地减去：

7 - len(days.split())

因此，您的代码可以简单地如下所示：

days = input("Which days had rain? ")
print("Number of days without rain: {}".format(7 - len(days.split())))

演示：

Which days had rain? m w f s
Number of days without rain: 3

或者：

Which days had rain? Monday Thursday
Number of days without rain: 5

首先，设day为可能天数的list

day = ['monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday', 'sunday']

然后，您应该输入：

days = raw_input("Which days had rain? ")

因为，您可以输入多天，您应该split它们。

input_list = days.split()

现在必须计算days列表中有多少个input？如何计算？

count=0  # counts the number of valid input days 
for input in input_list:  # insures you are checking all the inputs one by one
    if any(input in day for day in days): # check if input exists in the `days` list.
        count+=1

print len(days)-count

您不需要检查用户的输入是否有意义（例如，他们是否输入了有效的星期几）。

rainyDays = input("Which days had rain? ")
sepDay = rainyDays.split(' ')

for i in sepDay:
    indexOfDays = sepDay.index(i)
    x = 6 - indexOfDays
    if rainyDays == "":
        x = 7 - indexOfDays
print("Number of days without rain: " + str(x))

结果
哪几天下雨？星期一星期二星期三任何一天无雨天数：3
进程已完成，退出代码为0

data = input('Which days had rain? )
days = data.split()
print('Number of days without rain:', 7 - len(days))

这是它的示例代码和简单的方法.