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
• Can we assume this is case sensitive?
• Yes
• Can we use additional data structures?
• Yes
• Can we assume this fits in memory?
• Yes

## Test Cases¶

• None -> False
• '' -> True
• 'foo' -> False
• 'bar' -> 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 UniqueChars(object):

def has_unique_chars(self, string):
# TODO: Implement me
pass


## Unit Test¶

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

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

class TestUniqueChars(unittest.TestCase):

def test_unique_chars(self, func):
self.assertEqual(func(None), False)
self.assertEqual(func(''), True)
self.assertEqual(func('foo'), False)
self.assertEqual(func('bar'), True)
print('Success: test_unique_chars')

def main():
test = TestUniqueChars()
unique_chars = UniqueChars()
test.test_unique_chars(unique_chars.has_unique_chars)
try:
test.test_unique_chars(unique_chars_set.has_unique_chars)
unique_chars_in_place = UniqueCharsInPlace()
test.test_unique_chars(unique_chars_in_place.has_unique_chars)
except NameError:
# Alternate solutions are only defined
# in the solutions file
pass

if __name__ == '__main__':
main()


## Solution Notebook¶

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