Refactor linearPrimeSieve.js

src/algorithms/math/linear-prime-sieve/linearPrimeSieve.js

@@ -3,22 +3,33 @@
  * @return {number[]}
  */
 export default function linearPrimeSieve(maxNumber) {
-	const primes =[];
-	const leastPrimeFactor = new Array(maxNumber + 1).fill(0); // leastPrimeFactor[i] gives us the least prime factor of 'i'
-
-	for(let i=2; i<=maxNumber; i++ ){
-		if(!leastPrimeFactor[i]){ // leastPrimeFactor[i] = 0 means 'i' itself is its least prime factor, i.e 'i' is prime
-			leastPrimeFactor[i] = i;
-			primes.push(i);
-		}
-
-		/*
-		 *  start setting leastPrimeFactor[] for numbers 'x', where x = p * i, p is x's least prime factor and p <= leastPrimeFactor[i]
-		 *  x = p*i, this representation will be unique for any number, therefore leastPrimeFactor[x] will be set only once.
-		 */
-		for(let j=0; j<primes.length && primes[j]*i <=maxNumber && primes[j]<=leastPrimeFactor[i]; j++)
-			leastPrimeFactor[primes[j]*i] = primes[j];
-	}
-
-	return primes;
+  const primes = [];
+  // leastPrimeFactor[i] gives us the least prime factor of 'i'
+  const leastPrimeFactor = new Array(maxNumber + 1).fill(0);
+
+  for (let i = 2; i <= maxNumber; i += 1) {
+    if (!leastPrimeFactor[i]) {
+      /* leastPrimeFactor[i] = 0 means 'i' itself is its least prime factor,
+       * i.e 'i' is prime
+       */
+      leastPrimeFactor[i] = i;
+      primes.push(i);
+    }
+
+    /*
+     *  start setting leastPrimeFactor[] for numbers 'x', where x = p * i, p is x's
+     *  least prime factor and p <= leastPrimeFactor[i]. x = p*i, this representation will
+     *  be unique for any number, therefore leastPrimeFactor[x] will be
+     *  set only once.
+     */
+
+    let j = 0;
+    while (j < primes.length) {
+      if ((primes[j] * i > maxNumber) || (primes[j] > leastPrimeFactor[i])) { break; }
+      leastPrimeFactor[primes[j] * i] = primes[j];
+      j += 1;
+    }
+  }
+
+  return primes;
 }