019f8fd211
git-subtree-dir: users/wpcarro git-subtree-mainline:464bbcb15cgit-subtree-split:24f5a642afChange-Id: I6105b3762b79126b3488359c95978cadb3efa789
68 lines
2 KiB
Python
68 lines
2 KiB
Python
import unittest
|
|
|
|
|
|
# get_products_of_all_ints_except_at_index :: [Int] -> [Int]
|
|
def get_products_of_all_ints_except_at_index(xs):
|
|
n = len(xs)
|
|
if n < 2:
|
|
raise Exception("Cannot computer without 2 or elements")
|
|
# lhs
|
|
befores = [None] * n
|
|
befores[0] = 1
|
|
for i in range(1, n):
|
|
befores[i] = befores[i - 1] * xs[i - 1]
|
|
|
|
# rhs
|
|
afters = [None] * n
|
|
afters[-1] = 1
|
|
for i in range(n - 2, -1, -1):
|
|
afters[i] = afters[i + 1] * xs[i + 1]
|
|
|
|
result = [None] * n
|
|
for i in range(n):
|
|
result[i] = befores[i] * afters[i]
|
|
return result
|
|
|
|
|
|
# Tests
|
|
class Test(unittest.TestCase):
|
|
def test_small_list(self):
|
|
actual = get_products_of_all_ints_except_at_index([1, 2, 3])
|
|
expected = [6, 3, 2]
|
|
self.assertEqual(actual, expected)
|
|
|
|
def test_longer_list(self):
|
|
actual = get_products_of_all_ints_except_at_index([8, 2, 4, 3, 1, 5])
|
|
expected = [120, 480, 240, 320, 960, 192]
|
|
self.assertEqual(actual, expected)
|
|
|
|
def test_list_has_one_zero(self):
|
|
actual = get_products_of_all_ints_except_at_index([6, 2, 0, 3])
|
|
expected = [0, 0, 36, 0]
|
|
self.assertEqual(actual, expected)
|
|
|
|
def test_list_has_two_zeros(self):
|
|
actual = get_products_of_all_ints_except_at_index([4, 0, 9, 1, 0])
|
|
expected = [0, 0, 0, 0, 0]
|
|
self.assertEqual(actual, expected)
|
|
|
|
def test_one_negative_number(self):
|
|
actual = get_products_of_all_ints_except_at_index([-3, 8, 4])
|
|
expected = [32, -12, -24]
|
|
self.assertEqual(actual, expected)
|
|
|
|
def test_all_negative_numbers(self):
|
|
actual = get_products_of_all_ints_except_at_index([-7, -1, -4, -2])
|
|
expected = [-8, -56, -14, -28]
|
|
self.assertEqual(actual, expected)
|
|
|
|
def test_error_with_empty_list(self):
|
|
with self.assertRaises(Exception):
|
|
get_products_of_all_ints_except_at_index([])
|
|
|
|
def test_error_with_one_number(self):
|
|
with self.assertRaises(Exception):
|
|
get_products_of_all_ints_except_at_index([1])
|
|
|
|
|
|
unittest.main(verbosity=2)
|