'xrange' is a function in Python 2.x.
In Python 3.x, use range() function instead.

It's still likely to break things downstream because n/i will have a float type rather than int, doing annoying things like producing unwanted ".0" in printed output and str() conversions.

Really frustrating. I thought that initially as well and tailored my solution to it. When it was only letters and numbers, it passed. But with the random test cases I got a bunch of bugs, and now i have to write the code all over again( which I won't). all the different test cases should have been specified in the problem description . This is necessary because any one who tries to solve a problem needs to understand what test cases exist to write a solution around them.

Absolutely this ^. Really frustrating spending time trying to complete it only to see my approach was way off just because the instructions were not clear.

Completely agree and especially since all the sample tests follow this logic... Would it be possible to either make it clear in the instructions or to include a sample test which makes people understand the string might be a bit more complex than an alphabetical string followed by a numerical string?