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

# Challenge Notebook¶

## Constraints¶

• Can we assume the string is ASCII?
• Yes
• Note: Unicode strings could require special handling depending on your language
• Is this case sensitive?
• Yes
• Can we use additional data structures?
• Yes
• Can we assume this fits in memory?
• Yes

## Test Cases¶

• Any strings that differ in size -> False
• None, 'foo' -> False (any None results in False)
• ' ', 'foo' -> False
• ' ', ' ' -> True
• 'foobarbaz', 'barbazfoo' -> True

## 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 Rotation(object):

def is_substring(self, s1, s2):
# TODO: Implement me
pass

def is_rotation(self, s1, s2):
# TODO: Implement me
# Call is_substring only once
pass


## Unit Test¶

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

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

class TestRotation(unittest.TestCase):

def test_rotation(self):
rotation = Rotation()
self.assertEqual(rotation.is_rotation('o', 'oo'), False)
self.assertEqual(rotation.is_rotation(None, 'foo'), False)
self.assertEqual(rotation.is_rotation('', 'foo'), False)
self.assertEqual(rotation.is_rotation('', ''), True)
self.assertEqual(rotation.is_rotation('foobarbaz', 'barbazfoo'), True)
print('Success: test_rotation')

def main():
test = TestRotation()
test.test_rotation()

if __name__ == '__main__':
main()


## Solution Notebook¶

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