diff --git a/DIRECTORY.md b/DIRECTORY.md
index 7f6484cae5..5e8e1f401a 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -254,7 +254,6 @@
* [RowEchelon](Maths/RowEchelon.js)
* [ShorsAlgorithm](Maths/ShorsAlgorithm.js)
* [SieveOfEratosthenes](Maths/SieveOfEratosthenes.js)
- * [SieveOfEratosthenesIntArray](Maths/SieveOfEratosthenesIntArray.js)
* [Signum](Maths/Signum.js)
* [SimpsonIntegration](Maths/SimpsonIntegration.js)
* [Softmax](Maths/Softmax.js)
diff --git a/Maths/SieveOfEratosthenes.js b/Maths/SieveOfEratosthenes.js
index 01e141f2f0..681d8ba904 100644
--- a/Maths/SieveOfEratosthenes.js
+++ b/Maths/SieveOfEratosthenes.js
@@ -1,25 +1,26 @@
-const sieveOfEratosthenes = (n) => {
- /*
- * Calculates prime numbers till a number n
- * :param n: Number up to which to calculate primes
- * :return: A boolean list containing only primes
- */
- const primes = new Array(n + 1)
- primes.fill(true) // set all as true initially
- primes[0] = primes[1] = false // Handling case for 0 and 1
- const sqrtn = Math.ceil(Math.sqrt(n))
- for (let i = 2; i <= sqrtn; i++) {
- if (primes[i]) {
- for (let j = i * i; j <= n; j += i) {
- /*
- Optimization.
- Let j start from i * i, not 2 * i, because smaller multiples of i have been marked false.
+/**
+ * @function sieveOfEratosthenes
+ * @description Function to get all the prime numbers below a given number using sieve of eratosthenes algorithm
+ * @param {Number} max The limit below which all the primes are required to be
+ * @returns {Number[]} An array of all the prime numbers below max
+ * @see [Sieve of Eratosthenes](https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes)
+ * @example
+ * sieveOfEratosthenes(1) // ====> []
+ * @example
+ * sieveOfEratosthenes(20) // ====> [2, 3, 5, 7, 11, 13, 17, 19]
+ *
+ */
+function sieveOfEratosthenes(max) {
+ const sieve = []
+ const primes = []
- For example, let i = 4.
- We do not have to check from 8(4 * 2) to 12(4 * 3)
- because they have been already marked false when i=2 and i=3.
- */
- primes[j] = false
+ 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
}
}
}
diff --git a/Maths/SieveOfEratosthenesIntArray.js b/Maths/SieveOfEratosthenesIntArray.js
deleted file mode 100644
index 56336ce7d8..0000000000
--- a/Maths/SieveOfEratosthenesIntArray.js
+++ /dev/null
@@ -1,24 +0,0 @@
-/**
- * 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 }
diff --git a/Maths/test/SieveOfEratosthenes.test.js b/Maths/test/SieveOfEratosthenes.test.js
index 056693d39b..1a10b8bc7f 100644
--- a/Maths/test/SieveOfEratosthenes.test.js
+++ b/Maths/test/SieveOfEratosthenes.test.js
@@ -1,14 +1,29 @@
import { sieveOfEratosthenes } from '../SieveOfEratosthenes'
-import { PrimeCheck } from '../PrimeCheck'
-
-describe('should return an array of prime booleans', () => {
- it('should have each element in the array as a prime boolean', () => {
- const n = 30
- const primes = sieveOfEratosthenes(n)
- primes.forEach((primeBool, index) => {
- if (primeBool) {
- expect(PrimeCheck(index)).toBeTruthy()
- }
- })
+
+describe('sieveOfEratosthenes', () => {
+ test('returns an empty array for max < 2', () => {
+ expect(sieveOfEratosthenes(1)).toEqual([])
+ })
+
+ test('returns [2] for max = 2', () => {
+ expect(sieveOfEratosthenes(2)).toEqual([2])
+ })
+
+ test('returns [2, 3] for max = 3', () => {
+ expect(sieveOfEratosthenes(3)).toEqual([2, 3])
+ })
+
+ test('returns [2, 3, 5, 7] for max = 10', () => {
+ expect(sieveOfEratosthenes(10)).toEqual([2, 3, 5, 7])
+ })
+
+ test('returns [2, 3, 5, 7, 11, 13, 17, 19] for max = 20', () => {
+ expect(sieveOfEratosthenes(20)).toEqual([2, 3, 5, 7, 11, 13, 17, 19])
+ })
+
+ test('returns [2, 3, 5, 7, 11, 13, 17, 19, 23, 29] for max = 30', () => {
+ expect(sieveOfEratosthenes(30)).toEqual([
+ 2, 3, 5, 7, 11, 13, 17, 19, 23, 29
+ ])
})
})
diff --git a/Maths/test/SieveOfEratosthenesIntArray.test.js b/Maths/test/SieveOfEratosthenesIntArray.test.js
deleted file mode 100644
index e3a3be3002..0000000000
--- a/Maths/test/SieveOfEratosthenesIntArray.test.js
+++ /dev/null
@@ -1,12 +0,0 @@
-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()
- })
- })
-})
diff --git a/Project-Euler/Problem035.js b/Project-Euler/Problem035.js
index c877acba5a..0b11cd0357 100644
--- a/Project-Euler/Problem035.js
+++ b/Project-Euler/Problem035.js
@@ -9,7 +9,7 @@
*
* @author ddaniel27
*/
-import { sieveOfEratosthenes } from '../Maths/SieveOfEratosthenesIntArray'
+import { sieveOfEratosthenes } from '../Maths/SieveOfEratosthenes'
function problem35(n) {
if (n < 2) {
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