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import unittest
# Compute the fibonacci using a bottom-up algorithm.
def fib(n):
if n < 0:
raise Error('Cannot call fibonacci with negative values')
cache = [0, 1]
for i in range(n):
cache[0], cache[1] = cache[1], cache[0] + cache[1]
return cache[0]
# Compute the fibonacci using memoization.
def fib_memoized(n):
cache = {
0: 0,
1: 1,
}
def do_fib(n):
if n < 0:
raise Error('The fib function does not support negative inputs')
if n in cache:
return cache[n]
cache[n - 1] = do_fib(n - 1)
cache[n - 2] = do_fib(n - 2)
return cache[n - 1] + cache[n - 2]
return do_fib(n)
# Tests
class Test(unittest.TestCase):
def test_zeroth_fibonacci(self):
actual = fib(0)
expected = 0
self.assertEqual(actual, expected)
def test_first_fibonacci(self):
actual = fib(1)
expected = 1
self.assertEqual(actual, expected)
def test_second_fibonacci(self):
actual = fib(2)
expected = 1
self.assertEqual(actual, expected)
def test_third_fibonacci(self):
actual = fib(3)
expected = 2
self.assertEqual(actual, expected)
def test_fifth_fibonacci(self):
actual = fib(5)
expected = 5
self.assertEqual(actual, expected)
def test_tenth_fibonacci(self):
actual = fib(10)
expected = 55
self.assertEqual(actual, expected)
def test_negative_fibonacci(self):
with self.assertRaises(Exception):
fib(-1)
unittest.main(verbosity=2)
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