git-subtree-dir: users/wpcarro git-subtree-mainline:464bbcb15cgit-subtree-split:24f5a642afChange-Id: I6105b3762b79126b3488359c95978cadb3efa789
		
			
				
	
	
		
			59 lines
		
	
	
	
		
			1.5 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			59 lines
		
	
	
	
		
			1.5 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
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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