add code for isPowerFour

Author: Vaishnavi5Singh

src/main/java/com/thealgorithms/bitmanipulation/IsPowerFour.java

@@ -0,0 +1,29 @@
+package com.thealgorithms.bitmanipulation;
+
+/**
+ * Utility class for checking if a number is a power of four.
+ * A power of four is a number that can be expressed as 4^n where n is a non-negative integer.
+ * This class provides a method to determine if a given integer is a power of four using bit manipulation.
+ */
+public final class IsPowerFour {
+    private IsPowerFour() {
+    }
+
+    /**
+     * Checks if the given integer is a power of four.
+     *
+     * A number is considered a power of four if:
+     * - It is greater than zero
+     * - It is a power of two i.e. (n & (n - 1)) == 0
+     * - Its single set bit is in an even position — verified by (n & 0xAAAAAAAA) == 0
+     *
+     * @param number the integer to check
+     * @return true if the number is a power of false, false otherwise
+     */
+    public static boolean IsPowerFour(int number) {
+        if (number <= 0) {
+            return false;
+        }
+        return (number & (number - 1)) == 0 && (number & 0xAAAAAAAA) == 0;
+    }
+}

src/test/java/com/thealgorithms/bitmanipulation/IsPowerFourTest.java

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+package com.thealgorithms.bitmanipulation;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.stream.Stream;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+/**
+ * Test case for IsPowerFour class
+ */
+
+public class IsPowerTwoTest {
+
+    @ParameterizedTest
+    @MethodSource("provideNumbersForPowerFour")
+    public void testIsPowerFour(int number, boolean expected) {
+        if (expected) {
+            assertTrue(IsPowerFour.isPowerFour(number));
+        } else {
+            assertFalse(IsPowerFour.isPowerFour(number));
+        }
+    }
+
+    private static Stream<Arguments> provideNumbersForPowerFour() {
+        return Stream.of(
+                Arguments.of(1, Boolean.TRUE),     // 4^0
+                Arguments.of(4, Boolean.TRUE),     // 4^1
+                Arguments.of(16, Boolean.TRUE),    // 4^2
+                Arguments.of(64, Boolean.TRUE),    // 4^3
+                Arguments.of(256, Boolean.TRUE),   // 4^4
+                Arguments.of(1024, Boolean.FALSE), // 1024 = 2^10, not 4^n
+                Arguments.of(0, Boolean.FALSE),    // 0 is not a power of four
+                Arguments.of(-4, Boolean.FALSE),   // Negative number
+                Arguments.of(-16, Boolean.FALSE),  // Negative number
+                Arguments.of(2, Boolean.FALSE),    // 2 is not a power of four
+                Arguments.of(8, Boolean.FALSE),    // 8 = 2^3, not 4^n
+                Arguments.of(12, Boolean.FALSE),   // 12 is not a power of four
+                Arguments.of(20, Boolean.FALSE),   // 20 is not a power of four
+                Arguments.of(100, Boolean.FALSE),  // 100 is not a power of four
+                Arguments.of(4096, Boolean.TRUE)   // 4^6 = 4096
+        );
+    }
+}