From a2dbf5d892b865b3c0d1d1ea0cbe1e3477c28a44 Mon Sep 17 00:00:00 2001
From: vaibhav007jain <72961247+vaibhav007jain@users.noreply.github.com>
Date: Tue, 15 Mar 2022 21:09:20 +0530
Subject: [PATCH] BAEL-5385 Code for Automorphic Number. (#11928)

---
 .../automorphicnumber/AutomorphicNumber.java  | 31 +++++++++++++++++++
 .../AutomorphicNumberUnitTest.java            | 19 ++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 java-numbers-4/src/main/java/com/baeldung/automorphicnumber/AutomorphicNumber.java
 create mode 100644 java-numbers-4/src/test/java/com/baeldung/automorphicnumber/AutomorphicNumberUnitTest.java

diff --git a/java-numbers-4/src/main/java/com/baeldung/automorphicnumber/AutomorphicNumber.java b/java-numbers-4/src/main/java/com/baeldung/automorphicnumber/AutomorphicNumber.java
new file mode 100644
index 0000000000..926b13deda
--- /dev/null
+++ b/java-numbers-4/src/main/java/com/baeldung/automorphicnumber/AutomorphicNumber.java
@@ -0,0 +1,31 @@
+package com.baeldung.automorphicnumber;
+
+public class AutomorphicNumber {
+
+    public static void main(String[] args) {
+        System.out.println(isAutomorphicUsingLoop(76));
+        System.out.println(isAutomorphicUsingMath(76));
+    }
+
+    public static boolean isAutomorphicUsingMath(int number) {
+        int square = number * number;
+
+        int numberOfDigits = (int) Math.floor(Math.log10(number) + 1);
+        int lastDigits = (int) (square % (Math.pow(10, numberOfDigits)));
+
+        return number == lastDigits;
+    }
+
+    public static boolean isAutomorphicUsingLoop(int number) {
+        int square = number * number;
+
+        while (number > 0) {
+            if (number % 10 != square % 10) {
+                return false;
+            }
+            number /= 10;
+            square /= 10;
+        }
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/java-numbers-4/src/test/java/com/baeldung/automorphicnumber/AutomorphicNumberUnitTest.java b/java-numbers-4/src/test/java/com/baeldung/automorphicnumber/AutomorphicNumberUnitTest.java
new file mode 100644
index 0000000000..8e31de9f47
--- /dev/null
+++ b/java-numbers-4/src/test/java/com/baeldung/automorphicnumber/AutomorphicNumberUnitTest.java
@@ -0,0 +1,19 @@
+package com.baeldung.automorphicnumber;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+public class AutomorphicNumberUnitTest {
+
+    @Test
+    void givenANumber_whenPassed_thenShouldDetermineAutomorphicOrNot() {
+        int number1 = 76; // automorphic
+        int number2 = 16; // not automorphic 
+        assertTrue(AutomorphicNumber.isAutomorphicUsingLoop(number1));
+        assertFalse(AutomorphicNumber.isAutomorphicUsingLoop(number2));
+        assertTrue(AutomorphicNumber.isAutomorphicUsingMath(number1));
+        assertFalse(AutomorphicNumber.isAutomorphicUsingMath(number2));
+    }
+}