This notebook was prepared by Rishi Rajasekaran. Source and license info is available on Github.

# Challenge Notebook¶

## Constraints¶

• Is the input an integer representing the number of pairs?
• Yes
• Can we assume the inputs are valid?
• No
• Is the output a list of valid combinations?
• Yes
• Should the output have duplicates?
• No
• Can we assume this fits memory?
• Yes

## Test Cases¶

* None -> Exception
* Negative -> Exception
* 0 -> []
* 1 -> ['()']
* 2 -> ['(())', '()()']
* 3 -> ['((()))', '(()())', '(())()', '()(())', '()()()']

## 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 Parentheses(object):

def find_pair(self, num_pairs):
# TODO: implement me
pass

## Unit Test¶

In [ ]:
import unittest

class TestPairParentheses(unittest.TestCase):

def test_pair_parentheses(self):
parentheses = Parentheses()
self.assertRaises(TypeError, parentheses.find_pair, None)
self.assertRaises(ValueError, parentheses.find_pair, -1)
self.assertEqual(parentheses.find_pair(0), [])
self.assertEqual(parentheses.find_pair(1), ['()'])
self.assertEqual(parentheses.find_pair(2), ['(())',
'()()'])
self.assertEqual(parentheses.find_pair(3), ['((()))',
'(()())',
'(())()',
'()(())',
'()()()'])
print('Success: test_pair_parentheses')

def main():
test = TestPairParentheses()
test.test_pair_parentheses()

if __name__ == '__main__':
main()

## Solution Notebook¶

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