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Python Functional Python The Lambda Lambada Recursion

Tim Oltman
Tim Oltman
7,730 Points
Posted by Tim Oltman
Tim Oltman
7,730 Points

This question is extremely difficult or I'm just missing something here. Does it involve set unions?

This exercise is extremely difficult or I'm missing something very simple. It seems that set.add() only works for adding a single element to a set. Do we need to work with set unions for this question?

I'm very frustrated because usually these types of exercises only take a few minutes at the most if you have watched the videos and follow the instructions closely. I'm been at this for several hours at least over a couple of days.

courses.py 
courses = {'count': 2,
           'title': 'Django Basics',
           'prereqs': [{'count': 3,
                     'title': 'Object-Oriented Python',
                     'prereqs': [{'count': 1,
                               'title': 'Python Collections',
                               'prereqs': [{'count':0,
                                         'title': 'Python Basics',
                                         'prereqs': []}]},
                              {'count': 0,
                               'title': 'Python Basics',
                               'prereqs': []},
                              {'count': 0,
                               'title': 'Setting Up a Local Python Environment',
                               'prereqs': []}]},
                     {'count': 0,
                      'title': 'Flask Basics',
                      'prereqs': []}]}


def prereqs(data, pres=None):
  pres = pres or prereqs(data['prereqs']).add(data['title'])

  for course in data['prereqs']:
    prereqs(data['prereqs'])

2 Answers

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

You're close, but:

  • the original line that initializes "pres" should be left as-is
  • the loop should add the current item's title to "pres" before the recursive call
  • after the loop finishes, return "pres"
Tim Oltman
Tim Oltman
7,730 Points
Tim Oltman
Tim Oltman
7,730 Points

Thanks, I finally got it.