From db1f33ea5f799f5737bac1498d9c0cef124e05b8 Mon Sep 17 00:00:00 2001
From: Mansi5164 <156164354+Mansi5164@users.noreply.github.com>
Date: Wed, 29 Oct 2025 18:11:32 +0530
Subject: [PATCH 1/5] Added PowerOfFour algorithm in bitmanipulation

---
 .../bitmanipulation/PowerOfFour.java             | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java

diff --git a/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java b/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
new file mode 100644
index 000000000000..dfde4aa2646f
--- /dev/null
+++ b/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
@@ -0,0 +1,16 @@
+package bitmanipulation;
+
+public class PowerOfFour {
+    public static boolean isPowerOfFour(int n) {
+        // A power of 4 has only one bit set and that bit is at an even position
+        return n > 0 && (n & (n - 1)) == 0 && (n & 0x55555555) != 0;
+    }
+
+    public static void main(String[] args) {
+        int num = 64; // change to test other numbers
+        if (isPowerOfFour(num))
+            System.out.println(num + " is a power of 4.");
+        else
+            System.out.println(num + " is NOT a power of 4.");
+    }
+}

From 7dfe84e988544db24bef280aa53452c29d3ea25c Mon Sep 17 00:00:00 2001
From: Mansi5164 <156164354+Mansi5164@users.noreply.github.com>
Date: Wed, 29 Oct 2025 18:18:51 +0530
Subject: [PATCH 2/5] Moved PowerOfFour.java to main/java

---
 .../java/com/thealgorithms/bitmanipulation/PowerOfFour.java       | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename src/{test => main}/java/com/thealgorithms/bitmanipulation/PowerOfFour.java (100%)

diff --git a/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java b/src/main/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
similarity index 100%
rename from src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
rename to src/main/java/com/thealgorithms/bitmanipulation/PowerOfFour.java

From 08890bcc8e7ebc030ca0f82c459291516068ec3b Mon Sep 17 00:00:00 2001
From: Mansi5164 <156164354+Mansi5164@users.noreply.github.com>
Date: Wed, 29 Oct 2025 18:23:53 +0530
Subject: [PATCH 3/5] Fixed Checkstyle issues in PowerOfFour.java

---
 .../bitmanipulation/PowerOfFour.java             | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java

diff --git a/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java b/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
new file mode 100644
index 000000000000..a256b0816f2a
--- /dev/null
+++ b/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
@@ -0,0 +1,16 @@
+package com.thealgorithms.bitmanipulation;
+
+public class PowerOfFour {
+
+    private PowerOfFour() {
+        throw new IllegalStateException("Utility class");
+    }
+
+    public static boolean isPowerOfFour(int n) {
+        if (n <= 0) {
+            return false;
+        } else {
+            return (n & (n - 1)) == 0 && (n & 0x55555555) != 0;
+        }
+    }
+}

From 99f371b6eee339d65e87e88d7806d86d5f25211c Mon Sep 17 00:00:00 2001
From: Mansi5164 <156164354+Mansi5164@users.noreply.github.com>
Date: Wed, 29 Oct 2025 18:29:55 +0530
Subject: [PATCH 4/5] Fixed class name conflict and Checkstyle errors

---
 .../bitmanipulation/PowerOfFour.java          | 32 +++++++++++-------
 .../bitmanipulation/PowerOfFour.java          | 14 ++++++--
 .../bitmanipulation/PowerOfFourTest.java      | 33 +++++++++++++++++++
 3 files changed, 66 insertions(+), 13 deletions(-)
 create mode 100644 src/test/java/com/thealgorithms/bitmanipulation/PowerOfFourTest.java

diff --git a/src/main/java/com/thealgorithms/bitmanipulation/PowerOfFour.java b/src/main/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
index dfde4aa2646f..fde287f5415c 100644
--- a/src/main/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
+++ b/src/main/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
@@ -1,16 +1,26 @@
-package bitmanipulation;
+package com.thealgorithms.bitmanipulation;
 
-public class PowerOfFour {
-    public static boolean isPowerOfFour(int n) {
-        // A power of 4 has only one bit set and that bit is at an even position
-        return n > 0 && (n & (n - 1)) == 0 && (n & 0x55555555) != 0;
+/**
+ * This class provides a method to check if a given number is a power of four.
+ */
+public final class PowerOfFour {
+
+    // Private constructor to prevent instantiation
+    private PowerOfFour() {
+        throw new AssertionError("Cannot instantiate utility class");
     }
 
-    public static void main(String[] args) {
-        int num = 64; // change to test other numbers
-        if (isPowerOfFour(num))
-            System.out.println(num + " is a power of 4.");
-        else
-            System.out.println(num + " is NOT a power of 4.");
+    /**
+     * Checks whether the given integer is a power of four.
+     *
+     * @param n the number to check
+     * @return true if n is a power of four, false otherwise
+     */
+    public static boolean isPowerOfFour(int n) {
+        if (n <= 0) {
+            return false;
+        } else {
+            return (n & (n - 1)) == 0 && (n & 0x55555555) != 0;
+        }
     }
 }
diff --git a/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java b/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
index a256b0816f2a..fde287f5415c 100644
--- a/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
+++ b/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
@@ -1,11 +1,21 @@
 package com.thealgorithms.bitmanipulation;
 
-public class PowerOfFour {
+/**
+ * This class provides a method to check if a given number is a power of four.
+ */
+public final class PowerOfFour {
 
+    // Private constructor to prevent instantiation
     private PowerOfFour() {
-        throw new IllegalStateException("Utility class");
+        throw new AssertionError("Cannot instantiate utility class");
     }
 
+    /**
+     * Checks whether the given integer is a power of four.
+     *
+     * @param n the number to check
+     * @return true if n is a power of four, false otherwise
+     */
     public static boolean isPowerOfFour(int n) {
         if (n <= 0) {
             return false;
diff --git a/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFourTest.java b/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFourTest.java
new file mode 100644
index 000000000000..1d46f1202c8d
--- /dev/null
+++ b/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFourTest.java
@@ -0,0 +1,33 @@
+package com.thealgorithms.bitmanipulation;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for PowerOfFour class.
+ */
+public final class PowerOfFourTest {
+
+    @Test
+    void testPowerOfFourTrueCases() {
+        Assertions.assertTrue(PowerOfFour.isPowerOfFour(1));
+        Assertions.assertTrue(PowerOfFour.isPowerOfFour(4));
+        Assertions.assertTrue(PowerOfFour.isPowerOfFour(16));
+        Assertions.assertTrue(PowerOfFour.isPowerOfFour(64));
+    }
+
+    @Test
+    void testPowerOfFourFalseCases() {
+        Assertions.assertFalse(PowerOfFour.isPowerOfFour(0));
+        Assertions.assertFalse(PowerOfFour.isPowerOfFour(2));
+        Assertions.assertFalse(PowerOfFour.isPowerOfFour(8));
+        Assertions.assertFalse(PowerOfFour.isPowerOfFour(12));
+    }
+
+    @Test
+    void testNegativeNumbers() {
+        Assertions.assertFalse(PowerOfFour.isPowerOfFour(-4));
+        Assertions.assertFalse(PowerOfFour.isPowerOfFour(-16));
+    }
+}
+

From 07022c40f958ab40436d38d797d593ba96083b59 Mon Sep 17 00:00:00 2001
From: Mansi5164 <156164354+Mansi5164@users.noreply.github.com>
Date: Wed, 29 Oct 2025 18:33:13 +0530
Subject: [PATCH 5/5] Fix Checkstyle and rename test class to PowerOfFourTest

---
 .../java/com/thealgorithms/bitmanipulation/PowerOfFour.java   | 4 ++--
 .../com/thealgorithms/bitmanipulation/PowerOfFourTest.java    | 3 +--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/main/java/com/thealgorithms/bitmanipulation/PowerOfFour.java b/src/main/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
index fde287f5415c..f91f8412b3ce 100644
--- a/src/main/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
+++ b/src/main/java/com/thealgorithms/bitmanipulation/PowerOfFour.java
@@ -5,9 +5,9 @@
  */
 public final class PowerOfFour {
 
-    // Private constructor to prevent instantiation
+    /** Private constructor to prevent instantiation. */
     private PowerOfFour() {
-        throw new AssertionError("Cannot instantiate utility class");
+        throw new AssertionError("Cannot instantiate utility class.");
     }
 
     /**
diff --git a/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFourTest.java b/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFourTest.java
index 1d46f1202c8d..b202a58ed591 100644
--- a/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFourTest.java
+++ b/src/test/java/com/thealgorithms/bitmanipulation/PowerOfFourTest.java
@@ -4,7 +4,7 @@
 import org.junit.jupiter.api.Test;
 
 /**
- * Unit tests for PowerOfFour class.
+ * Unit tests for {@link PowerOfFour}.
  */
 public final class PowerOfFourTest {
 
@@ -30,4 +30,3 @@ void testNegativeNumbers() {
         Assertions.assertFalse(PowerOfFour.isPowerOfFour(-16));
     }
 }
-