Uncrypting a very simple code in python

So this is the brief: i need to input something like:

BaSe fOO ThE AttAcK

and return:

attack the base.

As you can see to decode this i need to start by reading the words in reverse order and if the first letter of the word isupper() then make it lowercase and append it to a list which i will later print. This is what i have so far:

# Enter your code for "BaSe fOO ThE AttAcK" here.
default = input('code: ')
listdefault = default.split()
uncrypted = []
for i in range(len(listdefault)):
  if listdefault[:-i].istitle(): # doesn't work
    i = i.lower() # dont know if this works, Should convert word to lower case.
    uncrypted.append(i)
solution = ' '.join(uncrypted)
print(solution)

Can someone show me how to get this program to work? Says that i can’t use the istitle() method on a list type..

Answer

You’re close, but you’re switching between treating i as an index (for i in range...) and as the word itself (uncrypted.append(i)). And you probably meant listdefault[i].istitle() rather than listdefault[:-i].istitle().

The best solution is to change it to:

for w in listdefault[::-1]:
    if w.istitle():
        w = w.lower()
        uncrypted.append(w)

Since listdefault[::-1] is a way to reverse the list (reversed(listdefault) also works). If you know how to use list comprehensions, you can do it in one line:

solution = ' '.join([w.lower() for w in listdefault[::-1] if w.istitle()])