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

Challenge Notebook¶

Problem: Determine if a number is a power of two.¶

Constraints¶

Is the input number an int?
- Yes
Can we assume the inputs are valid?
- No
Is the output a boolean?
- Yes
Can we assume this fits memory?
- Yes

Test Cases¶

None -> TypeError
0 -> False
1 -> True
2 -> True
15 -> False
16 -> 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 Solution(object):

    def is_power_of_two(self, val):
        # TODO: Implement me
        pass

Unit Test¶

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

In [ ]:

# %load test_is_power_of_two.py
import unittest


class TestSolution(unittest.TestCase):

    def test_is_power_of_two(self):
        solution = Solution()
        self.assertRaises(TypeError, solution.is_power_of_two, None)
        self.assertEqual(solution.is_power_of_two(0), False)
        self.assertEqual(solution.is_power_of_two(1), True)
        self.assertEqual(solution.is_power_of_two(2), True)
        self.assertEqual(solution.is_power_of_two(15), False)
        self.assertEqual(solution.is_power_of_two(16), True)
        print('Success: test_is_power_of_two')


def main():
    test = TestSolution()
    test.test_is_power_of_two()


if __name__ == '__main__':
    main()

Solution Notebook¶

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