One more solution and small fix for AmountOfPrimeNumbers

andrei-punko · andrei-punko · commit 288f47ea3297 · 2024-05-20T17:05:31.000+03:00
diff --git a/src/main/java/by/andd3dfx/numeric/AmountOfPrimeNumbers.java b/src/main/java/by/andd3dfx/numeric/AmountOfPrimeNumbers.java
@@ -12,7 +12,7 @@ public class AmountOfPrimeNumbers {
 
     public static int determine_usingPrimeDividersOfNumberSolution(int n) {
         int result = 0;
-        for (int i = 1; i < n; i++) {
+        for (int i = 2; i < n; i++) {
             if (isPrime(i)) {
                 result++;
             }
@@ -24,6 +24,25 @@ private static boolean isPrime(int number) {
         return PrimeDividersOfNumber.determine(number).length == 1;
     }
 
+    public static int determine_usingCustomIsPrimeWithEarlyReturn(int n) {
+        int result = 0;
+        for (int i = 2; i < n; i++) {
+            if (isPrimeEnhanced(i)) {
+                result++;
+            }
+        }
+        return result;
+    }
+
+    private static boolean isPrimeEnhanced(int number) {
+        for (int i = 2; i <= Math.sqrt(number); i++) {
+            if (number % i == 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     public static int determine_usingEratosthenesSieve(int n) {
         var isPrime = new boolean[n];
         Arrays.fill(isPrime, 2, n, true);
diff --git a/src/test/java/by/andd3dfx/numeric/AmountOfPrimeNumbersTest.java b/src/test/java/by/andd3dfx/numeric/AmountOfPrimeNumbersTest.java
@@ -13,6 +13,11 @@ public void testDetermine_usingPrimeDividersOfNumberSolution() {
         check(AmountOfPrimeNumbers::determine_usingPrimeDividersOfNumberSolution);
     }
 
+    @Test
+    public void testDetermine_usingCustomIsPrimeWithEarlyReturn() {
+        check(AmountOfPrimeNumbers::determine_usingCustomIsPrimeWithEarlyReturn);
+    }
+
     @Test
     public void testDetermine_usingEratosthenesSieve() {
         check(AmountOfPrimeNumbers::determine_usingEratosthenesSieve);
