Merge pull request TheAlgorithms#13 from ms10398/master

the-codingninja · web-flow · commit 2c6d14712dd2 · 2017-10-05T11:25:13.000+05:30
Added Implementation of Sieve Of Eratosthenes
diff --git a/Algorithms/sieveOfEratosthenes.js b/Algorithms/sieveOfEratosthenes.js
@@ -0,0 +1,31 @@
+function sieveOfEratosthenes (n) {
+	/*
+	* Calculates prime numbers till a number n
+	* :param n: Number upto which to calculate primes
+	* :return: A boolean list contaning only primes
+	*/
+	let primes = new Array(n + 1);
+	primes.fill(true);  // set all as true initially
+	primes[0] = primes[1] = false;  // Handling case for 0 and 1
+	let sqrtn = Math.ceil(Math.sqrt(n));
+	for (let i = 2; i <= sqrtn; i++) {
+		if (primes[i]) {
+			for (let j = 2 * i; j <= n; j += i) {
+				primes[j] = false;
+			}
+		}
+	}
+	return primes;
+}
+
+function main () {
+	let n = 69; // number till where we wish to find primes
+	let primes = sieveOfEratosthenes(n);
+	for (let i = 2; i <= n; i++) {
+		if (primes[i]) {
+			console.log(i);
+		}
+	}
+}
+
+main();
