Mar 14 2011
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Splitting list interview question

Just made this up, feels like a good interview question

Part 1 –

Write a function that takes a list and splits it at a specific percentage.

f(mylist, pct) = list(mylist[0 ... len(mylist) * pct / 100.0],
                      mylist[len(mylist) * pct / 100.0 ... EOL])

Part 2 -

Now generalize that so that f(mylist, ..) takes an arbitrary number of percentages (in order) and returns you the list. This is interesting as an interview questions since I can see a bunch of interesting things coming up in the white board coding session.

  • How to deal with short lists, more percentages than list items
  • Approaches that end up with overlapping items (item #20 in the list twice)
  • General familiarity of the language of choice
  • How they understanding basic list processing – this is one list controlling the handling of another list.

Then again, somebody might pull a fast one on you and make you go huh?

# python code
def split_list(mylist, *args):
    # ilist not necessary, but makes formatting easier
    ilist = map(lambda p : int(p * len(mylist) / 100.0), args) + [len(mylist)]
    return reduce(lambda l, v : [l[0] + [mylist[l[1]:v]], v], ilist, [[],0])[0]