From b3a6f3bc47098c81bef2c7d16690a5801149dbd8 Mon Sep 17 00:00:00 2001
From: Haidong Ji
Date: Sun, 19 Aug 2018 15:28:15 -0500
Subject: Least Common Multiple done!

Learned two interesting things:
1. Use GCD to get LCM https://www.idomaths.com/hcflcm.php#formula
2. To make a literal of numbers long, add L at the end of the number!---
 AlgoDesignAndTechniqueEdxJava/sources/GCD.java     | 24 -----------
 AlgoDesignAndTechniqueEdxJava/sources/GcdLcm.java  | 29 +++++++++++++
 AlgoDesignAndTechniqueEdxJava/tests/GCDTest.java   | 33 ---------------
 .../tests/GcdLcmTest.java                          | 48 ++++++++++++++++++++++
 4 files changed, 77 insertions(+), 57 deletions(-)
 delete mode 100644 AlgoDesignAndTechniqueEdxJava/sources/GCD.java
 create mode 100644 AlgoDesignAndTechniqueEdxJava/sources/GcdLcm.java
 delete mode 100644 AlgoDesignAndTechniqueEdxJava/tests/GCDTest.java
 create mode 100644 AlgoDesignAndTechniqueEdxJava/tests/GcdLcmTest.java

diff --git a/AlgoDesignAndTechniqueEdxJava/sources/GCD.java b/AlgoDesignAndTechniqueEdxJava/sources/GCD.java
deleted file mode 100644
index 5e29e4f..0000000
--- a/AlgoDesignAndTechniqueEdxJava/sources/GCD.java
+++ /dev/null
@@ -1,24 +0,0 @@
-import java.util.Scanner;
-
-public class GCD {
-
-	public static int getGCD(int a, int b) {
-		if (b == 0) {
-			return a;
-		}
-
-		if (b > a) {
-			return getGCD(b, a);
-		} else {
-			return getGCD(b, a % b);
-		}
-	}
-
-	public static void main(String args[]) {
-		Scanner in = new Scanner(System.in);
-		int a = in.nextInt();
-		int b = in.nextInt();
-
-		System.out.println(getGCD(a, b));
-	}
-}
diff --git a/AlgoDesignAndTechniqueEdxJava/sources/GcdLcm.java b/AlgoDesignAndTechniqueEdxJava/sources/GcdLcm.java
new file mode 100644
index 0000000..efef982
--- /dev/null
+++ b/AlgoDesignAndTechniqueEdxJava/sources/GcdLcm.java
@@ -0,0 +1,29 @@
+import java.util.Scanner;
+
+public class GcdLcm {
+
+	public static int getGCD(int a, int b) {
+		if (b == 0) {
+			return a;
+		}
+
+		if (b > a) {
+			return getGCD(b, a);
+		} else {
+			return getGCD(b, a % b);
+		}
+	}
+
+	public static void main(String args[]) {
+		Scanner in = new Scanner(System.in);
+		int a = in.nextInt();
+		int b = in.nextInt();
+
+		System.out.println(getLCM(a, b));
+	}
+
+	public static long getLCM(int a, int b) {
+		// https://www.idomaths.com/hcflcm.php#formula
+		return (long) a * (long) b / (long) getGCD(a, b);
+	}
+}
diff --git a/AlgoDesignAndTechniqueEdxJava/tests/GCDTest.java b/AlgoDesignAndTechniqueEdxJava/tests/GCDTest.java
deleted file mode 100644
index 1c8fedd..0000000
--- a/AlgoDesignAndTechniqueEdxJava/tests/GCDTest.java
+++ /dev/null
@@ -1,33 +0,0 @@
-import static org.junit.jupiter.api.Assertions.*;
-import org.junit.jupiter.api.Test;
-
-public class GCDTest {
-	@Test
-	void testGCD1() {
-		assertEquals(1, GCD.getGCD(18, 35));
-	}
-	@Test
-	void testGCD2() {
-		assertEquals(17657, GCD.getGCD(28851538, 1183019));
-	}
-
-	@Test
-	void testGCD3() {
-		assertEquals(7, GCD.getGCD(1344, 217));
-	}
-
-	@Test
-	void testGCD4() {
-		assertEquals(1344, GCD.getGCD(1344, 1344));
-	}
-
-	@Test
-	void testGCD5() {
-		assertEquals(4, GCD.getGCD(14159572, 63967072));
-	}
-
-	@Test
-	void testGCD6() {
-		assertEquals(4, GCD.getGCD(63967072,14159572));
-	}
-}
diff --git a/AlgoDesignAndTechniqueEdxJava/tests/GcdLcmTest.java b/AlgoDesignAndTechniqueEdxJava/tests/GcdLcmTest.java
new file mode 100644
index 0000000..26806ce
--- /dev/null
+++ b/AlgoDesignAndTechniqueEdxJava/tests/GcdLcmTest.java
@@ -0,0 +1,48 @@
+import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.Test;
+
+public class GcdLcmTest {
+	@Test
+	void testGCD1() {
+		assertEquals(1, GcdLcm.getGCD(18, 35));
+	}
+	@Test
+	void testGCD2() {
+		assertEquals(17657, GcdLcm.getGCD(28851538, 1183019));
+	}
+
+	@Test
+	void testGCD3() {
+		assertEquals(7, GcdLcm.getGCD(1344, 217));
+	}
+
+	@Test
+	void testGCD4() {
+		assertEquals(1344, GcdLcm.getGCD(1344, 1344));
+	}
+
+	@Test
+	void testGCD5() {
+		assertEquals(4, GcdLcm.getGCD(14159572, 63967072));
+	}
+
+	@Test
+	void testGCD6() {
+		assertEquals(4, GcdLcm.getGCD(63967072,14159572));
+	}
+
+	@Test
+	void testLCM1() {
+		assertEquals(24, GcdLcm.getLCM(6,8));
+	}
+
+	@Test
+	void testLCM2() {
+		assertEquals(1933053046, GcdLcm.getLCM(28851538, 1183019));
+	}
+
+	@Test
+	void testLCM3() {
+		assertEquals(226436590403296L, GcdLcm.getLCM(14159572, 63967072));
+	}
+}
-- 
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