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Commit36828b1

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Julien00859poyea
authored andcommitted
[FIX] maths/PrimeCheck (TheAlgorithms#796)
Current implementation is buggy and hard to read.* Negative values were raising a TypeError due to `math.sqrt`* 1 was considered prime, it is not.* 2 was considered not prime, it is.The implementation has been corrected to fix the bugs and to enhancereadability.A docstring has been added with the definition of a prime number.A complete test suite has been written, it tests the 10 first primes, anegative value, 0, 1 and some not prime numbers.closesTheAlgorithms#795
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‎maths/PrimeCheck.py

Lines changed: 48 additions & 7 deletions
Original file line numberDiff line numberDiff line change
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importmath
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importunittest
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defprimeCheck(number):
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ifnumber%2==0andnumber>2:
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"""
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A number is prime if it has exactly two dividers: 1 and itself.
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"""
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ifnumber<2:
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# Negatives, 0 and 1 are not primes
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returnFalse
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returnall(number%iforiinrange(3,int(math.sqrt(number))+1,2))
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ifnumber<4:
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# 2 and 3 are primes
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returnTrue
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ifnumber%2==0:
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# Even values are not primes
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returnFalse
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# Except 2, all primes are odd. If any odd value divide
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# the number, then that number is not prime.
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odd_numbers=range(3,int(math.sqrt(number))+1,2)
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returnnotany(number%i==0foriinodd_numbers)
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classTest(unittest.TestCase):
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deftest_primes(self):
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self.assertTrue(primeCheck(2))
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self.assertTrue(primeCheck(3))
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self.assertTrue(primeCheck(5))
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self.assertTrue(primeCheck(7))
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self.assertTrue(primeCheck(11))
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self.assertTrue(primeCheck(13))
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self.assertTrue(primeCheck(17))
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self.assertTrue(primeCheck(19))
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self.assertTrue(primeCheck(23))
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self.assertTrue(primeCheck(29))
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deftest_not_primes(self):
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self.assertFalse(primeCheck(-19),
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"Negative numbers are not prime.")
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self.assertFalse(primeCheck(0),
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"Zero doesn't have any divider, primes must have two")
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self.assertFalse(primeCheck(1),
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"One just have 1 divider, primes must have two.")
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self.assertFalse(primeCheck(2*2))
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self.assertFalse(primeCheck(2*3))
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self.assertFalse(primeCheck(3*3))
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self.assertFalse(primeCheck(3*5))
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self.assertFalse(primeCheck(3*5*7))
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defmain():
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print(primeCheck(37))
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print(primeCheck(100))
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print(primeCheck(77))
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if__name__=='__main__':
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main()
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unittest.main()
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