82 lines
2.1 KiB
Python
82 lines
2.1 KiB
Python
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import unittest
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import sys
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import trace
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def highest_product_of_3(xs):
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if len(xs) < 3:
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raise Exception("List needs to contain at least three elements.")
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hp3 = xs[0] * xs[1] * xs[2]
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hp2 = xs[0] * xs[1]
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lp2 = xs[0] * xs[1]
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hn = max(xs[0], xs[1])
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ln = min(xs[0], xs[1])
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for x in xs[2:]:
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hp3 = max(hp3, hp2 * x, lp2 * x)
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hp2 = max(hp2, hn * x, ln * x)
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lp2 = min(lp2, hn * x, ln * x)
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hn = max(hn, x)
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ln = min(ln, x)
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return hp3
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# Tests
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class Test(unittest.TestCase):
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def test_short_list(self):
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actual = highest_product_of_3([1, 2, 3, 4])
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expected = 24
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self.assertEqual(actual, expected)
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def test_longer_list(self):
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actual = highest_product_of_3([6, 1, 3, 5, 7, 8, 2])
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expected = 336
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self.assertEqual(actual, expected)
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def test_list_has_one_negative(self):
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actual = highest_product_of_3([-5, 4, 8, 2, 3])
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expected = 96
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self.assertEqual(actual, expected)
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def test_list_has_two_negatives(self):
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actual = highest_product_of_3([-10, 1, 3, 2, -10])
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expected = 300
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self.assertEqual(actual, expected)
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def test_list_is_all_negatives(self):
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actual = highest_product_of_3([-5, -1, -3, -2])
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expected = -6
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self.assertEqual(actual, expected)
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def test_error_with_empty_list(self):
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with self.assertRaises(Exception):
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highest_product_of_3([])
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def test_error_with_one_number(self):
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with self.assertRaises(Exception):
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highest_product_of_3([1])
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def test_error_with_two_numbers(self):
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with self.assertRaises(Exception):
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highest_product_of_3([1, 1])
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def test_custom(self):
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actual = highest_product_of_3([9, 5, 2, 1, 7, 3])
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expected = 9 * 7 * 5
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self.assertEqual(actual, expected)
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unittest.main(verbosity=2)
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def main():
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highest_product_of_3([-5, -1, -3, -2])
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tracer = trace.Trace(ignoredirs=[sys.prefix, sys.exec_prefix],
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trace=0,
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count=1)
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tracer.run('main()')
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r = tracer.results()
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r.write_results(show_missing=True, coverdir=".")
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