Add first coding challenge

Author: soycode

.gitignore

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+*.pyc

cc1/README.md

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+This is a coding challenge for students in Lambda School's Machine Learning
+course. It covers some of the basic mathematical functions that appear in
+reinforcement learning.
+
+# Instructions for students
+
+Visit this article:
+https://medium.freecodecamp.org/an-introduction-to-reinforcement-learning-4339519de419
+
+Read up to the line  "To be simple, each reward will be discounted by `gamma` to
+the exponent of the time step." Today we'll be implementing the equation
+immediately above that. For simplicity we'll assume that each round has a fixed
+reward `R` and that the only thing changing the utility is the discount.
+
+Your task is to calculate the total lifetime reward for a given `R` and `gamma`.
+You should clone this repository, open it up locally, and open the file
+`reward.py`. You'll see an empty function called `reward(gamma, R)`. Right now
+it's set to return -1.0. Change it so that it returns the correct answer.
+THIS IS THE ONLY FILE YOU SHOULD EDIT.
+
+A resource to review summation notation:
+http://www.columbia.edu/itc/sipa/math/summation.html
+
+## Testing your solution
+
+The correctness of your code will be tested with `unittest`, a testing library
+built in to Python. You can run tests in this directory as follows:
+
+`python test_reward.py --verbose`
+
+Depending on your computer it may be `python3` instead. And also the `--verbose`
+flag is optional, but helpfully expands the output.
+
+This command will run the tests contained in `test_reward.py` - you do not
+need to edit this file, but please do check it out to see how it works. Unit
+tests usually test expected input/output of a short function (a "unit" - in this
+case the function `reward()` you are writing).
+
+This particular test file has one always passing test and four tests that will
+pass once you successfully complete the `reward()` function. The always passing
+test is for you to be sure you're running the test properly - even before
+writing code you should see 1 success and 4 failures if you run the tests.
+
+If you're curious about `unittest` you can read more here:
+https://docs.python.org/3.6/library/unittest.html
+
+With a few exceptions if you know enough mathematics, there is no good way for a
+program to calculate the exact value of an infinite sum. Besides the inherent
+trickiness of infinite sums, this is true because of the unavoidable
+approximateness of floating point arithmetic. Because of this, the tests are
+written such that your result has to be within 1/1000th of the answer.

cc1/reward.py

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+def reward(R, gamma):
+	return -1.0  # TODO

cc1/test_reward.py

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+import unittest
+from reward import reward
+
+
+class TestReward(unittest.TestCase):
+
+    def test_always_passing_test(self):
+        self.assertEqual(3 + 1, 4)
+
+    def test_reward_1(self):
+        self.assertAlmostEqual(reward(-2.1, 0.32), -3.0882352, 3)
+
+    def test_reward_2(self):
+	    self.assertAlmostEqual(reward(-0.1, 0.55), -0.222222, 3)
+
+    def test_reward_3(self):
+	    self.assertAlmostEqual(reward(3.2, 0.95), 64.0, 3)
+
+    def test_reward_4(self):
+	    self.assertAlmostEqual(reward(3.0, 0.79), 14.285714, 3)
+
+
+if __name__ == '__main__':
+    unittest.main()