Gigs_ wrote: > Can someone explain me this > def f(l): > if l == []: > return [] > else: > return f(l[1:]) + l[:1] # <= cant figure this, how is > all sum at the end?
If you think about building up from the simplest case: f([]) = [] f(['a']) = f([]) + ['a'] = [] + ['a'] = ['a'] Now f(['a', 'b']) is going to be: f(['b']) + ['a'] = ['b'] + ['a'] = ['b', 'a'] Similarly, for f(['a', 'b', 'c']), that will be: f(['b', 'c']) + ['a'] Of course, if you want to do this you can always use list.reverse() but I guess you're trying to get a handle on recursion rather than just reverse a list. I find thinking up from the base case helps when trying to understand recursive code but when writing it, I tend to work the other way around. -- I'm at CAMbridge, not SPAMbridge -- http://mail.python.org/mailman/listinfo/python-list
