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

Challenge Notebook¶

Problem: Sort an array of strings so all anagrams are next to each other.¶

Constraints
Test Cases
Algorithm
Code
Unit Test
Solution Notebook

Constraints¶

Are there any other sorting requirements other than the grouping of anagrams?
- No
Can we assume the inputs are valid?
- No
Can we assume this fits memory?
- Yes

Test Cases¶

None -> Exception
[] -> []
General case
- Input: ['ram', 'act', 'arm', 'bat', 'cat', 'tab']
- Result: ['arm', 'ram', 'act', 'cat', 'bat', 'tab']

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 [ ]:

from collections import OrderedDict


class Anagram(object):

    def group_anagrams(self, items):
        # TODO: Implement me
        pass

Unit Test¶

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

In [ ]:

# %load test_anagrams.py
import unittest


class TestAnagrams(unittest.TestCase):

    def test_group_anagrams(self):
        anagram = Anagram()
        self.assertRaises(TypeError, anagram.group_anagrams, None)
        data = ['ram', 'act', 'arm', 'bat', 'cat', 'tab']
        expected = ['ram', 'arm', 'act', 'cat', 'bat', 'tab']
        self.assertEqual(anagram.group_anagrams(data), expected)

        print('Success: test_group_anagrams')


def main():
    test = TestAnagrams()
    test.test_group_anagrams()


if __name__ == '__main__':
    main()

Solution Notebook¶

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