This notebook was prepared by Donne Martin. Source and license info is on GitHub.

Challenge Notebook

Constraints

  • Is the input a list?
    • Yes
  • Can we assume the inputs are valid?
    • Check for None in place of an array
    • Assume array elements are ints
  • Do we know the max digits to handle?
    • No
  • Are the digits base 10?
    • Yes
  • Can we assume this fits memory?
    • Yes

Test Cases

  • None -> Exception
  • [] -> []
  • [128, 256, 164, 8, 2, 148, 212, 242, 244] -> [2, 8, 128, 148, 164, 212, 242, 244, 256]

Algorithm

Refer to the Solution Notebook. If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start.

Code

In [ ]:
class RadixSort(object):

    def sort(self, array, base=10):
        # TODO: Implement me
        pass

Unit Test

The following unit test is expected to fail until you solve the challenge.

In [ ]:
# %load test_radix_sort.py
import unittest


class TestRadixSort(unittest.TestCase):

    def test_sort(self):
        radix_sort = RadixSort()
        self.assertRaises(TypeError, radix_sort.sort, None)
        self.assertEqual(radix_sort.sort([]), [])
        array = [128, 256, 164, 8, 2, 148, 212, 242, 244]
        expected = [2, 8, 128, 148, 164, 212, 242, 244, 256]
        self.assertEqual(radix_sort.sort(array), expected)
        print('Success: test_sort')


def main():
    test = TestRadixSort()
    test.test_sort()


if __name__ == '__main__':
    main()

Solution Notebook

Review the Solution Notebook for a discussion on algorithms and code solutions.