tvl-depot/users/wpcarro/scratch/data_structures_and_algorithms/nth-fibonacci.py
Vincent Ambo 019f8fd211 subtree(users/wpcarro): docking briefcase at '24f5a642'
git-subtree-dir: users/wpcarro
git-subtree-mainline: 464bbcb15c
git-subtree-split: 24f5a642af
Change-Id: I6105b3762b79126b3488359c95978cadb3efa789
2021-12-14 02:15:47 +03:00

59 lines
1.5 KiB
Python

import unittest
################################################################################
# Solution
################################################################################
def fib(n):
"""This should be accomplishable in O(1) space."""
if n in {0, 1}:
return n
a = 0 # i = 0
b = 1 # i = 1
for x in range(2, n + 1):
result = a + b
a = b
b = result
return result
################################################################################
# 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)