Complete practice algorithms from InterviewCake.com
While I've done these algorithms before, I'm preparing for an on-site with DeepMind, so I created a subdirectory called deepmind where I'm storing my second attempts at these problems. The idea of storing them in a second directory is to remove the urge to check my existing solutions that also exist in this repository.
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51
deepmind/inflight-entertainment.py
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51
deepmind/inflight-entertainment.py
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import unittest
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def can_two_movies_fill_flight(xs, t):
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seeking = set()
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for x in xs:
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if x in seeking:
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return True
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else:
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seeking.add(t - x)
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return False
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# Tests
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class Test(unittest.TestCase):
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def test_short_flight(self):
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result = can_two_movies_fill_flight([2, 4], 1)
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self.assertFalse(result)
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def test_long_flight(self):
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result = can_two_movies_fill_flight([2, 4], 6)
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self.assertTrue(result)
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def test_one_movie_half_flight_length(self):
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result = can_two_movies_fill_flight([3, 8], 6)
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self.assertFalse(result)
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def test_two_movies_half_flight_length(self):
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result = can_two_movies_fill_flight([3, 8, 3], 6)
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self.assertTrue(result)
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def test_lots_of_possible_pairs(self):
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result = can_two_movies_fill_flight([1, 2, 3, 4, 5, 6], 7)
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self.assertTrue(result)
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def test_not_using_first_movie(self):
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result = can_two_movies_fill_flight([4, 3, 2], 5)
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self.assertTrue(result)
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def test_only_one_movie(self):
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result = can_two_movies_fill_flight([6], 6)
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self.assertFalse(result)
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def test_no_movies(self):
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result = can_two_movies_fill_flight([], 2)
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self.assertFalse(result)
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unittest.main(verbosity=2)
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59
deepmind/merging-ranges.py
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deepmind/merging-ranges.py
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import unittest
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def merge_ranges(xs):
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xs.sort()
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result = [xs[0]]
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for curr in xs[1:]:
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a, z = result[-1]
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if z >= curr[0]:
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result[-1] = (a, max(z, curr[1]))
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else:
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result.append(curr)
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return result
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# Tests
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class Test(unittest.TestCase):
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def test_meetings_overlap(self):
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actual = merge_ranges([(1, 3), (2, 4)])
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expected = [(1, 4)]
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self.assertEqual(actual, expected)
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def test_meetings_touch(self):
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actual = merge_ranges([(5, 6), (6, 8)])
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expected = [(5, 8)]
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self.assertEqual(actual, expected)
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def test_meeting_contains_other_meeting(self):
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actual = merge_ranges([(1, 8), (2, 5)])
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expected = [(1, 8)]
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self.assertEqual(actual, expected)
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def test_meetings_stay_separate(self):
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actual = merge_ranges([(1, 3), (4, 8)])
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expected = [(1, 3), (4, 8)]
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self.assertEqual(actual, expected)
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def test_multiple_merged_meetings(self):
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actual = merge_ranges([(1, 4), (2, 5), (5, 8)])
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expected = [(1, 8)]
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self.assertEqual(actual, expected)
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def test_meetings_not_sorted(self):
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actual = merge_ranges([(5, 8), (1, 4), (6, 8)])
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expected = [(1, 4), (5, 8)]
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self.assertEqual(actual, expected)
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def test_one_long_meeting_contains_smaller_meetings(self):
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actual = merge_ranges([(1, 10), (2, 5), (6, 8), (9, 10), (10, 12)])
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expected = [(1, 12)]
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self.assertEqual(actual, expected)
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def test_sample_input(self):
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actual = merge_ranges([(0, 1), (3, 5), (4, 8), (10, 12), (9, 10)])
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expected = [(0, 1), (3, 8), (9, 12)]
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self.assertEqual(actual, expected)
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unittest.main(verbosity=2)
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51
deepmind/stock-price.py
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deepmind/stock-price.py
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def get_max_profit(xs):
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best_profit = xs[1] - xs[0]
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lowest_buy = xs[0]
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for x in xs[1:]:
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best_profit = max(best_profit, x - lowest_buy)
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lowest_buy = min(lowest_buy, x)
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return best_profit
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# Tests
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import unittest
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class Test(unittest.TestCase):
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def test_price_goes_up_then_down(self):
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actual = get_max_profit([1, 5, 3, 2])
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expected = 4
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self.assertEqual(actual, expected)
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def test_price_goes_down_then_up(self):
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actual = get_max_profit([7, 2, 8, 9])
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expected = 7
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self.assertEqual(actual, expected)
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def test_price_goes_up_all_day(self):
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actual = get_max_profit([1, 6, 7, 9])
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expected = 8
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self.assertEqual(actual, expected)
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def test_price_goes_down_all_day(self):
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actual = get_max_profit([9, 7, 4, 1])
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expected = -2
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self.assertEqual(actual, expected)
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def test_price_stays_the_same_all_day(self):
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actual = get_max_profit([1, 1, 1, 1])
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expected = 0
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self.assertEqual(actual, expected)
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def test_error_with_empty_prices(self):
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with self.assertRaises(Exception):
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get_max_profit([])
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def test_error_with_one_price(self):
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with self.assertRaises(Exception):
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get_max_profit([1])
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unittest.main(verbosity=2)
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