Add tests for power using recursion algorithm (#4335)

src/main/java/com/thealgorithms/maths/PowRecursion.java

@@ -1,23 +0,0 @@
-package com.thealgorithms.maths;
-
-public class PowRecursion {
-
-    public static void main(String[] args) {
-        assert Double.compare(pow(2, 0), Math.pow(2, 0)) == 0;
-        assert Double.compare(pow(0, 2), Math.pow(0, 2)) == 0;
-        assert Double.compare(pow(2, 10), Math.pow(2, 10)) == 0;
-        assert Double.compare(pow(10, 2), Math.pow(10, 2)) == 0;
-    }
-
-    /**
-     * Returns the value of the first argument raised to the power of the second
-     * argument
-     *
-     * @param a the base.
-     * @param b the exponent.
-     * @return the value {@code a}<sup>{@code b}</sup>.
-     */
-    public static long pow(int a, int b) {
-        return b == 0 ? 1 : a * pow(a, b - 1);
-    }
-}

src/main/java/com/thealgorithms/maths/PowerUsingRecursion.java

@@ -0,0 +1,20 @@
+package com.thealgorithms.maths;
+
+/**
+ * calculate Power using Recursion
+ * @author Bama Charan Chhandogi (https://github.com/BamaCharanChhandogi)
+ */
+
+public class PowerUsingRecursion {
+
+    public static double power(double base, int exponent) {
+        // Base case: anything raised to the power of 0 is 1
+        if (exponent == 0) {
+            return 1;
+        }
+
+        // Recursive case: base ^ exponent = base * base ^ (exponent - 1)
+        // Recurse with a smaller exponent and multiply with base
+        return base * power(base, exponent - 1);
+    }
+}

src/test/java/com/thealgorithms/maths/PowerUsingRecursionTest.java

@@ -0,0 +1,20 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Test case for Power using Recursion
+ * @author Bama Charan Chhandogi (https://github.com/BamaCharanChhandogi)
+ */
+
+class PowerUsingRecursionTest {
+
+    @Test
+    void testPowerUsingRecursion() {
+        assertEquals(32.0, PowerUsingRecursion.power(2.0, 5));
+        assertEquals(97.65625, PowerUsingRecursion.power(2.5, 5));
+        assertEquals(81, PowerUsingRecursion.power(3, 4));
+    }
+}