60 lines
1.5 KiB
Python
60 lines
1.5 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 fib(n):
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"""This should be accomplishable in O(1) space."""
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if n in {0, 1}:
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return n
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a = 0 # i = 0
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b = 1 # i = 1
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for x in range(2, n + 1):
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result = a + b
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a = b
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b = result
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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_zeroth_fibonacci(self):
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actual = fib(0)
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expected = 0
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self.assertEqual(actual, expected)
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def test_first_fibonacci(self):
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actual = fib(1)
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expected = 1
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self.assertEqual(actual, expected)
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def test_second_fibonacci(self):
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actual = fib(2)
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expected = 1
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self.assertEqual(actual, expected)
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def test_third_fibonacci(self):
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actual = fib(3)
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expected = 2
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self.assertEqual(actual, expected)
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def test_fifth_fibonacci(self):
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actual = fib(5)
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expected = 5
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self.assertEqual(actual, expected)
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def test_tenth_fibonacci(self):
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actual = fib(10)
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expected = 55
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self.assertEqual(actual, expected)
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def test_negative_fibonacci(self):
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with self.assertRaises(Exception):
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fib(-1)
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unittest.main(verbosity=2)
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