algorithm: sieve (#1205)

Maths/SieveOfEratosthenesIntArray.js

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+/**
+ * Function to get all prime numbers below a given number
+ * This function returns an array of prime numbers
+ * @see {@link https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes}
+ */
+
+function sieveOfEratosthenes (max) {
+  const sieve = []
+  const primes = []
+
+  for (let i = 2; i <= max; ++i) {
+    if (!sieve[i]) { // If i has not been marked then it is prime
+      primes.push(i)
+      for (let j = i << 1; j <= max; j += i) { // Mark all multiples of i as non-prime
+        sieve[j] = true
+      }
+    }
+  }
+  return primes
+}
+
+export { sieveOfEratosthenes }

Maths/test/SieveOfEratosthenesIntArray.test.js

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+import { sieveOfEratosthenes } from '../SieveOfEratosthenesIntArray'
+import { PrimeCheck } from '../PrimeCheck'
+
+describe('should return an array of prime numbers', () => {
+  it('should have each element in the array as a prime numbers', () => {
+    const n = 100
+    const primes = sieveOfEratosthenes(n)
+    primes.forEach(prime => {
+      expect(PrimeCheck(prime)).toBeTruthy()
+    })
+  })
+})