class ThreeSum:
def __init__(self):
self.two_sum_obj = TwoSum()
def twoSum(self, inputs, sum_for_comparison):
# not to access any input element twice
# todo: extend this function to deal with non-unique inputs, additional data structure to store counts of uniques and computation changes
# exactly one solution
# integers
assert inputs.dtype == np.int
hash_table = {}
for curr_idx, curr_input in enumerate(inputs):
complement_curr_input = sum_for_comparison - curr_input
if complement_curr_input in hash_table:
assert curr_idx != hash_table[complement_curr_input]
return hash_table[complement_curr_input], curr_idx
hash_table[curr_input] = curr_idx
return None, None
def threeSum(self, inputs):
# not to access any input element twice
# integers
# assert inputs.dtype == np.int
all_tuples = []
for curr_idx, curr_input in enumerate(inputs):
complement_curr_input = -curr_input
inputs_complement = np.concatenate(
(inputs[:curr_idx], inputs[curr_idx + 1:]))
curr_idx2, curr_idx3 = self.two_sum_obj.twoSum(
inputs=inputs_complement,
sum_for_comparison=complement_curr_input,
)
if curr_idx2 is None:
assert curr_idx3 is None
continue
if curr_idx2 >= curr_idx:
curr_idx2 += 1
if curr_idx3 >= curr_idx:
curr_idx3 += 1
curr_tuple = [
inputs[curr_idx],
inputs[curr_idx2],
inputs[curr_idx3],
]
curr_tuple.sort()
if curr_tuple not in all_tuples:
all_tuples.append(curr_tuple)
return all_tuples
def test_WithProperValues_ShouldReturnCorrectIndices(self):
# arrange
input = [2, 7, 11, 15]
target = 9
expected_output = [ 0, 1 ]
# act
actual_output = TwoSum().two_sum_solver(input, target)
# assert
self.assertListEqual(expected_output, actual_output)
def test_WithNoAnswer_ShouldReturn00(self):
# arrange
input = [2,3,4]
target = 9
expected_output = [0, 0]
# act
actual_output = TwoSum().two_sum_solver(input, target)
# assert
self.assertListEqual(expected_output, actual_output)
def test_WithFewInputs_ShouldReturnNone(self):
# arrange
input = [2]
target = 9
expected_output = None
# act
actual_output = TwoSum().two_sum_solver(input, target)
# assert
self.assertEqual(expected_output, actual_output),
class TestTwoSum(unittest.TestCase):
def setUp(self):
self.two_sum = TwoSum()
def tearDown(self):
del self.two_sum
def test_twosum_should_return_empty_when_input_is_None(self):
self.assertEqual(self.two_sum.two_sum(None, 3), [])
def test_twosum_should_return_empty_when_input_isempty(self):
self.assertEqual(self.two_sum.two_sum([], 3), [])
def test_twosum_should_raise_exception_when_target_can_not_be_achieved(
self):
with self.assertRaises(Exception):
self.two_sum.two_sum([1, 5, 10], 3)
def test_twosum_should_return_two_elements_which_sums_to_target(self):
res = sum(self.two_sum.two_sum([1, 5, 10, 2], 3))
self.assertEqual(res, 3)
def setUp(self):
self.two_sum = TwoSum()
def test_two_sum(self):
self.assertEqual([0, 1], TwoSum.two_sum(nums=[2, 7, 11, 15], target=9))
def __init__(self):
self.two_sum_obj = TwoSum()