Finished

.gitignore

@@ -22,3 +22,6 @@
 # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid*
 replay_pid*
+
+# IntelliJ IDEA
+.idea

gcd.iml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

src/Main.java

@@ -0,0 +1,50 @@
+import java.util.ArrayList;
+import java.util.List;
+
+public class Main {
+    public static void main(String[] args) {
+        int a = 48;
+        int b = 18;
+
+        int normalResult = normalGcd(a, b);
+        int euclideanResult = euclideanGcd(a, b);
+
+        System.out.printf("Normal gcd: %d%n", normalResult);
+        System.out.printf("Euclidean gcd: %d%n", euclideanResult);
+    }
+
+    public static int normalGcd(int a, int b) {
+        List<Integer> factorsA = primeFactors(a);
+        List<Integer> factorsB = primeFactors(b);
+        int gcd = 1;
+        for (int i = 0; i < factorsA.size(); i++) {
+            int factor = factorsA.get(i);
+            if (factorsB.contains(factor)) {
+                gcd *= factor;
+                factorsB.remove((Integer) factor);
+            }
+        }
+        return gcd;
+    }
+
+    private static List<Integer> primeFactors(int n) {
+        List<Integer> factors = new ArrayList<>();
+        for (int i = 2; i * i <= n; i++) {
+            while (n % i == 0) {
+                factors.add(i);
+                n /= i;
+            }
+        }
+        if (n > 1) factors.add(n);
+        return factors;
+    }
+
+    public static int euclideanGcd(int a, int b) {
+        while (b != 0) {
+            int temp = b;
+            b = a % b;
+            a = temp;
+        }
+        return a;
+    }
+}