def test_primes(self):
self.assertListEqual([2, 3, 5, 7], get_primes(7))
self.assertRaises(ValueError, get_primes, -42)
def test_primes(self):
self.assertListEqual([2, 3, 5, 7], get_primes(7))
self.assertRaises(ValueError, get_primes, -42)
""" Return list of all primes less than n, Using sieve of Eratosthenes. Modification: We don't need to check all even numbers, we can make the sieve excluding even numbers and adding 2 to the primes list by default. We are going to make an array of: x / 2 - 1 if number is even, else x / 2 (The -1 with even number it's to exclude the number itself) Because we just need numbers [from 3..x if x is odd] # We can get value represented at index i with (i*2 + 3) For example, for x = 10, we start with an array of x / 2 - 1 = 4 [1, 1, 1, 1] 3 5 7 9 For x = 11: [1, 1, 1, 1, 1] 3 5 7 9 11 # 11 is odd, it's included in the list With this, we have reduced the array size to a half, and complexity it's also a half now. """ from algorithms.maths import get_primes print(get_primes(100))
