#!/usr/bin/env python
# coding: utf-8

# This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges).

# # Challenge Notebook

# ## Problem: Determine the number of bits to flip to convert int a to int b'.
# 
# * [Constraints](#Constraints)
# * [Test Cases](#Test-Cases)
# * [Algorithm](#Algorithm)
# * [Code](#Code)
# * [Unit Test](#Unit-Test)
# * [Solution Notebook](#Solution-Notebook)

# ## Constraints
# 
# * Can we assume A and B are always ints?
#     * Yes
# * Is the output an int?
#     * Yes
# * Can we assume A and B are always the same number of bits?
#     * Yes
# * Can we assume the inputs are valid (not None)?
#     * No
# * Can we assume this fits memory?
#     * Yes

# ## Test Cases
# 
# * A or B is None -> Exception
# * General case
# <pre>
#     A = 11101
#     B = 01111
#     Result: 2
# <pre>

# ## 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 Bits(object):

    def bits_to_flip(self, a, b):
        # TODO: Implement me
        pass


# ## Unit Test

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

# In[ ]:


# %load test_bits_to_flip.py
import unittest


class TestBits(unittest.TestCase):

    def test_bits_to_flip(self):
        bits = Bits()
        a = int('11101', base=2)
        b = int('01111', base=2)
        expected = 2
        self.assertEqual(bits.bits_to_flip(a, b), expected)
        print('Success: test_bits_to_flip')


def main():
    test = TestBits()
    test.test_bits_to_flip()


if __name__ == '__main__':
    main()


# ## Solution Notebook
# 
# Review the [Solution Notebook]() for a discussion on algorithms and code solutions.