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author | Vincent Ambo <mail@tazj.in> | 2021-12-13T22·51+0300 |
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committer | Vincent Ambo <mail@tazj.in> | 2021-12-13T23·15+0300 |
commit | 019f8fd2113df4c5247c3969c60fd4f0e08f91f7 (patch) | |
tree | 76a857f61aa88f62a30e854651e8439db77fd0ea /users/wpcarro/scratch/data_structures_and_algorithms/product-of-other-numbers.py | |
parent | 464bbcb15c09813172c79820bcf526bb10cf4208 (diff) | |
parent | 6123e976928ca3d8d93f0b2006b10b5f659eb74d (diff) |
subtree(users/wpcarro): docking briefcase at '24f5a642' r/3226
git-subtree-dir: users/wpcarro git-subtree-mainline: 464bbcb15c09813172c79820bcf526bb10cf4208 git-subtree-split: 24f5a642af3aa1627bbff977f0a101907a02c69f Change-Id: I6105b3762b79126b3488359c95978cadb3efa789
Diffstat (limited to 'users/wpcarro/scratch/data_structures_and_algorithms/product-of-other-numbers.py')
-rw-r--r-- | users/wpcarro/scratch/data_structures_and_algorithms/product-of-other-numbers.py | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/users/wpcarro/scratch/data_structures_and_algorithms/product-of-other-numbers.py b/users/wpcarro/scratch/data_structures_and_algorithms/product-of-other-numbers.py new file mode 100644 index 000000000000..d05e82d42b02 --- /dev/null +++ b/users/wpcarro/scratch/data_structures_and_algorithms/product-of-other-numbers.py @@ -0,0 +1,68 @@ +import unittest + + +################################################################################ +# Solution +################################################################################ +# f :: [Int] -> [Int] +def get_products_of_all_ints_except_at_index(xs): + if len(xs) in {0, 1}: + raise Exception + + ct = len(xs) + lefts = [1] * ct + rights = [1] * ct + result = [] + + for i in range(1, ct): + lefts[i] = lefts[i - 1] * xs[i - 1] + for i in range(ct - 2, -1, -1): + rights[i] = rights[i + 1] * xs[i + 1] + + return [lefts[i] * rights[i] for i in range(ct)] + + +################################################################################ +# 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) |