Add fibonacci template and unit tests for recursion and memoization

Author: neptunius

Diff for: source/recursion.py

@@ -0,0 +1,55 @@
+#!python
+
+def fibonacci(n):
+    """fibonacci(n) returns the n-th number in the Fibonacci sequence,
+    which is defined with the recurrence relation:
+    fibonacci(0) = 0
+    fibonacci(1) = 1
+    fibonacci(n) = fibonacci(n - 1) + fibonacci(n - 2), for n > 1"""
+    # Check if n is negative or not an integer (invalid input)
+    if n < 0 or not isinstance(n, int):
+        raise ValueError('fibonacci is undefined for n = {!r}'.format(n))
+    # Implement fibonacci_recursive, _memoized, and _dynamic below, then
+    # change this to call your implementation to verify it passes all tests
+    return fibonacci_recursive(n)
+    # return fibonacci_memoized(n)
+    # return fibonacci_dynamic(n)
+
+
+def fibonacci_recursive(n):
+    # Check if n is one of the base cases
+    if n == 0 or n == 1:
+        return n
+    # Check if n is larger than the base cases
+    elif n > 1:
+        # Call function recursively and add the results together
+        return fibonacci_recursive(n - 1) + fibonacci_recursive(n - 2)
+
+
+def fibonacci_memoized(n):
+    # TODO: Memoize the fibonacci function's recursive implementation here
+    pass
+    # Once implemented, change fibonacci (above) to call fibonacci_memoized
+    # to verify that your memoized implementation passes all test cases
+
+
+def fibonacci_dynamic(n):
+    # TODO: Implement the fibonacci function with dynamic programming here
+    pass
+    # Once implemented, change fibonacci (above) to call fibonacci_dynamic
+    # to verify that your dynamic implementation passes all test cases
+
+
+def main():
+    import sys
+    args = sys.argv[1:]  # Ignore script file name
+    if len(args) == 1:
+        num = int(args[0])
+        result = fibonacci(num)
+        print('fibonacci({}) => {}'.format(num, result))
+    else:
+        print('Usage: {} number'.format(sys.argv[0]))
+
+
+if __name__ == '__main__':
+    main()

Diff for: source/recursion_test.py

@@ -0,0 +1,51 @@
+#!python
+
+from recursion import fibonacci
+import unittest
+
+
+class RecursionTest(unittest.TestCase):
+    def test_fibonacci_with_small_integers(self):
+        # Known fibonacci numbers with small integer arguments
+        assert fibonacci(0) == 0  # base case
+        assert fibonacci(1) == 1  # base case
+        assert fibonacci(2) == 1
+        assert fibonacci(3) == 2
+        assert fibonacci(4) == 3
+        assert fibonacci(5) == 5
+        assert fibonacci(6) == 8
+        assert fibonacci(7) == 13
+        assert fibonacci(8) == 21
+        assert fibonacci(9) == 34
+        assert fibonacci(10) == 55
+
+    def test_fibonacci_with_large_integers(self):
+        # These could run for a long time, depending on your implementation...
+        assert fibonacci(15) == 610
+        assert fibonacci(20) == 6765
+        assert fibonacci(25) == 75025
+        # TODO: Improve the runtime of your fibonacci function for these cases
+        # If you're not careful, you may need to be very patient for these...
+        # assert fibonacci(30) == 832040
+        # assert fibonacci(35) == 9227465
+        # assert fibonacci(40) == 102334155
+
+    def test_fibonacci_with_negative_integers(self):
+        # Should raise a ValueError for n < 0
+        with self.assertRaises(ValueError):
+            fibonacci(-1)
+        with self.assertRaises(ValueError):
+            fibonacci(-5)
+
+    def test_fibonacci_with_floating_point_numbers(self):
+        # Should raise a ValueError for non-integer n
+        with self.assertRaises(ValueError):
+            fibonacci(2.0)
+        with self.assertRaises(ValueError):
+            fibonacci(3.14159)
+        with self.assertRaises(ValueError):
+            fibonacci('5')
+
+
+if __name__ == '__main__':
+    unittest.main()