/team-int-code-challenge

Primary LanguagePython

Python Tech Challenge

The challenge is to create a program that computes some basic statistics on a collection of small positive integers. You can assume all values will be less than 1,000.

Requirements

The DataCapture object accepts numbers and returns an object for the querying statistics about the inputs. Specifically, the returned object supports querying how many numbers in the collection are less than a value, greater than a value, or within a range.

Here's the program skeleton in python to explain the structure:

datacapture = DataCapture()
datacapture.add(3)
datacapture.add(9)
datacapture.add(3)
datacapture.add(4)
datacapture.add(6)
stats = datacapture.build_stats()
stats.less(4) # should return 2 (only two values 3, 3 are less than 4)
stats.between(3, 6) # should return 4 (3, 3, 4 and 6 are between 3 and 6)
stats.greater(4) # should return 2 (6 and  9 are the only two values greater than 4)

Challenge Conditions

  • You cannot import a library that solves it instantly.
  • The methods add(), less(), greater(), and between() should have a constant time O(1)
  • The method build_stats() can be at most linear O(n)
  • Apply the best practices you know
  • Share a public repo with your project

Solution

I've proposed a solution that involves the following

DataCapture

A class that allows you to add numbers to the list and compute the statistics through the build_stats method.

add

Add a number to the list of numbers to evaluate

build_stats

Iterates over the internal _counts property, . At the same time, it creates an object for each number in it. the internal dictionary contains the following keys:

  • less: Since the internal dict is supposed to be in order, we add to less the current number’s counter less += self._counts[number]
  • greater: Since the internal dict is supposed to be in order, we subtract to greater the current number’s counter greater -= self._counts[number]
  • count: We make it equals to the current number’s count inside the internal counter self._counts (dict) stats._counts[number]['count'] = self._counts[number]

Stats

A class that makes the computations

This class contains the following methods:

less

Returns the number of items in the list that are less than the number passed in.

greater

Returns the number of items in the list that are greater than the number passed in.

between

Returns the number of items in the list that are between the lower and upper bounds passed in.

Setup

I am using Python 3.9, however other versions can be supported too.

  • Clone the repo.
  • cd to the folder.
  • Create a virtual environment.
  • Activate it.

Usage

If you want to see the driver_code running run the command: python driver_code.py Also you can start your own shell with the .env file, import the DataCapture class and execute your own code.

Testing

Run the command: PYTHONPATH=./src python tests/test_data_capture.py