mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-18 01:00:15 +00:00
38dfcd28b5
1. Incorrect function was being imported from the module 2. Testing for exception was not done correctly
84 lines
2.1 KiB
Python
84 lines
2.1 KiB
Python
"""Prime Check."""
|
|
|
|
import math
|
|
import unittest
|
|
|
|
|
|
def is_prime(number: int) -> bool:
|
|
"""Checks to see if a number is a prime in O(sqrt(n)).
|
|
|
|
A number is prime if it has exactly two factors: 1 and itself.
|
|
|
|
>>> is_prime(0)
|
|
False
|
|
>>> is_prime(1)
|
|
False
|
|
>>> is_prime(2)
|
|
True
|
|
>>> is_prime(3)
|
|
True
|
|
>>> is_prime(27)
|
|
False
|
|
>>> is_prime(87)
|
|
False
|
|
>>> is_prime(563)
|
|
True
|
|
>>> is_prime(2999)
|
|
True
|
|
>>> is_prime(67483)
|
|
False
|
|
"""
|
|
|
|
# precondition
|
|
assert isinstance(number, int) and (
|
|
number >= 0
|
|
), "'number' must been an int and positive"
|
|
|
|
if 1 < number < 4:
|
|
# 2 and 3 are primes
|
|
return True
|
|
elif number < 2 or number % 2 == 0 or number % 3 == 0:
|
|
# Negatives, 0, 1, all even numbers, all multiples of 3 are not primes
|
|
return False
|
|
|
|
# All primes number are in format of 6k +/- 1
|
|
for i in range(5, int(math.sqrt(number) + 1), 6):
|
|
if number % i == 0 or number % (i + 2) == 0:
|
|
return False
|
|
return True
|
|
|
|
|
|
class Test(unittest.TestCase):
|
|
def test_primes(self):
|
|
self.assertTrue(is_prime(2))
|
|
self.assertTrue(is_prime(3))
|
|
self.assertTrue(is_prime(5))
|
|
self.assertTrue(is_prime(7))
|
|
self.assertTrue(is_prime(11))
|
|
self.assertTrue(is_prime(13))
|
|
self.assertTrue(is_prime(17))
|
|
self.assertTrue(is_prime(19))
|
|
self.assertTrue(is_prime(23))
|
|
self.assertTrue(is_prime(29))
|
|
|
|
def test_not_primes(self):
|
|
with self.assertRaises(AssertionError):
|
|
is_prime(-19)
|
|
self.assertFalse(
|
|
is_prime(0),
|
|
"Zero doesn't have any positive factors, primes must have exactly two.",
|
|
)
|
|
self.assertFalse(
|
|
is_prime(1),
|
|
"One only has 1 positive factor, primes must have exactly two.",
|
|
)
|
|
self.assertFalse(is_prime(2 * 2))
|
|
self.assertFalse(is_prime(2 * 3))
|
|
self.assertFalse(is_prime(3 * 3))
|
|
self.assertFalse(is_prime(3 * 5))
|
|
self.assertFalse(is_prime(3 * 5 * 7))
|
|
|
|
|
|
if __name__ == "__main__":
|
|
unittest.main()
|