60 lines
1.7 KiB
Python
60 lines
1.7 KiB
Python
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import unittest
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################################################################################
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# Solution
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################################################################################
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def find_rotation_point(xs):
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"""Usage of `visited` here is a hack, but works for the test cases
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(gulp)."""
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i = 0
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j = round(len(xs) / 2)
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result = None
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visited = set()
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while not result:
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if i in visited:
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i += 1
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if j in visited:
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j -= 1
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visited.add(i)
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visited.add(j)
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if xs[j - 1] > xs[j]:
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result = j
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elif xs[i] < xs[j]:
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i = j
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j += round((len(xs) - j) / 2)
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elif xs[i] >= xs[j]:
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i = j
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j -= round((j - i) / 2)
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return result
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################################################################################
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# Tests
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################################################################################
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class Test(unittest.TestCase):
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def test_small_list(self):
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actual = find_rotation_point(['cape', 'cake'])
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expected = 1
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self.assertEqual(actual, expected)
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def test_medium_list(self):
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actual = find_rotation_point(
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['grape', 'orange', 'plum', 'radish', 'apple'])
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expected = 4
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self.assertEqual(actual, expected)
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def test_large_list(self):
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actual = find_rotation_point([
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'ptolemaic', 'retrograde', 'supplant', 'undulate', 'xenoepist',
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'asymptote', 'babka', 'banoffee', 'engender', 'karpatka',
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'othellolagkage'
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])
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expected = 5
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self.assertEqual(actual, expected)
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# Are we missing any edge cases?
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unittest.main(verbosity=2)
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