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authorVincent Ambo <mail@tazj.in>2021-12-13T22·51+0300
committerVincent Ambo <mail@tazj.in>2021-12-13T23·15+0300
commit019f8fd2113df4c5247c3969c60fd4f0e08f91f7 (patch)
tree76a857f61aa88f62a30e854651e8439db77fd0ea /users/wpcarro/scratch/deepmind/part_two/highest-product-of-3.py
parent464bbcb15c09813172c79820bcf526bb10cf4208 (diff)
parent6123e976928ca3d8d93f0b2006b10b5f659eb74d (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/deepmind/part_two/highest-product-of-3.py')
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diff --git a/users/wpcarro/scratch/deepmind/part_two/highest-product-of-3.py b/users/wpcarro/scratch/deepmind/part_two/highest-product-of-3.py
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+++ b/users/wpcarro/scratch/deepmind/part_two/highest-product-of-3.py
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+import unittest
+import sys
+import trace
+
+
+def highest_product_of_3(xs):
+    if len(xs) < 3:
+        raise Exception("List needs to contain at least three elements.")
+    hp3 = xs[0] * xs[1] * xs[2]
+    hp2 = xs[0] * xs[1]
+    lp2 = xs[0] * xs[1]
+    hn = max(xs[0], xs[1])
+    ln = min(xs[0], xs[1])
+    for x in xs[2:]:
+        hp3 = max(hp3, hp2 * x, lp2 * x)
+        hp2 = max(hp2, hn * x, ln * x)
+        lp2 = min(lp2, hn * x, ln * x)
+        hn = max(hn, x)
+        ln = min(ln, x)
+    return hp3
+
+
+# Tests
+class Test(unittest.TestCase):
+    def test_short_list(self):
+        actual = highest_product_of_3([1, 2, 3, 4])
+        expected = 24
+        self.assertEqual(actual, expected)
+
+    def test_longer_list(self):
+        actual = highest_product_of_3([6, 1, 3, 5, 7, 8, 2])
+        expected = 336
+        self.assertEqual(actual, expected)
+
+    def test_list_has_one_negative(self):
+        actual = highest_product_of_3([-5, 4, 8, 2, 3])
+        expected = 96
+        self.assertEqual(actual, expected)
+
+    def test_list_has_two_negatives(self):
+        actual = highest_product_of_3([-10, 1, 3, 2, -10])
+        expected = 300
+        self.assertEqual(actual, expected)
+
+    def test_list_is_all_negatives(self):
+        actual = highest_product_of_3([-5, -1, -3, -2])
+        expected = -6
+        self.assertEqual(actual, expected)
+
+    def test_error_with_empty_list(self):
+        with self.assertRaises(Exception):
+            highest_product_of_3([])
+
+    def test_error_with_one_number(self):
+        with self.assertRaises(Exception):
+            highest_product_of_3([1])
+
+    def test_error_with_two_numbers(self):
+        with self.assertRaises(Exception):
+            highest_product_of_3([1, 1])
+
+    def test_custom(self):
+        actual = highest_product_of_3([9, 5, 2, 1, 7, 3])
+        expected = 9 * 7 * 5
+        self.assertEqual(actual, expected)
+
+
+unittest.main(verbosity=2)
+
+
+def main():
+    highest_product_of_3([-5, -1, -3, -2])
+
+
+tracer = trace.Trace(ignoredirs=[sys.prefix, sys.exec_prefix],
+                     trace=0,
+                     count=1)
+
+tracer.run('main()')
+r = tracer.results()
+r.write_results(show_missing=True, coverdir=".")