Add HigherLowerPowerOfTwo algorithm (#5707)

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

@@ -0,0 +1,26 @@
+package com.thealgorithms.bitmanipulation;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class HigherLowerPowerOfTwoTest {
+
+    @Test
+    public void testNextHigherPowerOfTwo() {
+        assertEquals(32, HigherLowerPowerOfTwo.nextHigherPowerOfTwo(19)); // next higher power of two is 32
+        assertEquals(1, HigherLowerPowerOfTwo.nextHigherPowerOfTwo(1)); // next higher power of two is 1
+        assertEquals(16, HigherLowerPowerOfTwo.nextHigherPowerOfTwo(15)); // next higher power of two is 16
+        assertEquals(8, HigherLowerPowerOfTwo.nextHigherPowerOfTwo(8)); // next higher power of two is 8
+        assertEquals(16, HigherLowerPowerOfTwo.nextHigherPowerOfTwo(9)); // next higher power of two is 16
+    }
+
+    @Test
+    public void testNextLowerPowerOfTwo() {
+        assertEquals(16, HigherLowerPowerOfTwo.nextLowerPowerOfTwo(19)); // next lower power of two is 16
+        assertEquals(1, HigherLowerPowerOfTwo.nextLowerPowerOfTwo(1)); // next lower power of two is 1
+        assertEquals(8, HigherLowerPowerOfTwo.nextLowerPowerOfTwo(9)); // next lower power of two is 8
+        assertEquals(8, HigherLowerPowerOfTwo.nextLowerPowerOfTwo(15)); // next lower power of two is 8
+        assertEquals(8, HigherLowerPowerOfTwo.nextLowerPowerOfTwo(8)); // next lower power of two is 8
+    }
+}