BAEL-3116: Finding the Least Common Multiple in Java

- Add tutorial to implement algorithms used for computing
  LCM of two or more numbers.
- List of Algorithms covered:
  - Simple Method
  - Prime Factorization Method
  - Euclidean Algorithm
  - BigInteger Class for large numbers
  - Lambda Implementation for LCM of more than two numbers
- Reference: BAEL-3116

java-numbers-2/src/test/java/com/baeldung/lcm/BigIntegerLCMUnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung.lcm;
+
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.math.BigInteger;
+
+public class BigIntegerLCMUnitTest {
+
+    @Test
+    public void testLCM() {
+        BigInteger number1 = new BigInteger("12");
+        BigInteger number2 = new BigInteger("18");
+        BigInteger expectedLCM = new BigInteger("36");
+        Assert.assertEquals(expectedLCM, BigIntegerLCM.lcm(number1, number2));
+    }
+}

java-numbers-2/src/test/java/com/baeldung/lcm/EuclideanAlgorithmUnitTest.java

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+package com.baeldung.lcm;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class EuclideanAlgorithmUnitTest {
+
+    @Test
+    public void testGCD() {
+        Assert.assertEquals(6, EuclideanAlgorithm.gcd(12, 18));
+    }
+
+    @Test
+    public void testLCM() {
+        Assert.assertEquals(36, EuclideanAlgorithm.lcm(12, 18));
+    }
+
+    @Test
+    public void testLCMForArray() {
+        Assert.assertEquals(15, EuclideanAlgorithm.lcmForArray(new int[]{3, 5, 15}));
+    }
+
+    @Test
+    public void testLCMByLambdaForArray() {
+        Assert.assertEquals(15, EuclideanAlgorithm.lcmByLambda(new int[]{3, 5, 15}));
+    }
+}

java-numbers-2/src/test/java/com/baeldung/lcm/PrimeFactorizationAlgorithmUnitTest.java

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+package com.baeldung.lcm;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static com.baeldung.lcm.PrimeFactorizationAlgorithm.*;
+
+
+public class PrimeFactorizationAlgorithmUnitTest {
+
+    @Test
+    public void testGetPrimeFactors() {
+        Map<Integer, Integer> expectedPrimeFactorsMapForTwelve = new HashMap<>();
+        expectedPrimeFactorsMapForTwelve.put(2, 2);
+        expectedPrimeFactorsMapForTwelve.put(3, 1);
+        Map<Integer, Integer> expectedPrimeFactorsMapForEighteen = new HashMap<>();
+        expectedPrimeFactorsMapForEighteen.put(2, 1);
+        expectedPrimeFactorsMapForEighteen.put(3, 2);
+        Assert.assertEquals(expectedPrimeFactorsMapForTwelve, getPrimeFactors(12));
+        Assert.assertEquals(expectedPrimeFactorsMapForEighteen, getPrimeFactors(18));
+    }
+
+    @Test
+    public void testLCM() {
+        Assert.assertEquals(36, PrimeFactorizationAlgorithm.lcm(12, 18));
+    }
+}

java-numbers-2/src/test/java/com/baeldung/lcm/SimpleAlgorithmUnitTest.java

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+package com.baeldung.lcm;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import static com.baeldung.lcm.SimpleAlgorithm.*;
+
+public class SimpleAlgorithmUnitTest {
+
+    @Test
+    public void testLCM() {
+        Assert.assertEquals(36, lcm(12, 18));
+    }
+
+}