Nov 15, 2025 · Nov 15, 2025 · Nov 15, 2025
diff --git a/src/main/java/com/thealgorithms/maths/PowerUsingRecursion.java b/src/main/java/com/thealgorithms/maths/PowerUsingRecursion.java

 /**
 * calculate Power using Recursion
 * @authorBama Charan Chhandogi(https://github.com/BamaCharanChhandogi)
 * @authorVinayak(https://github.com/Vinayak-v12)
 */

 public final class PowerUsingRecursion {
    private PowerUsingRecursion() {
    }

    /**
     * Computes base raised to the given exponent.
     *
     * @param base the number to be raised
     * @param exponent the power (can be negative)
     * @return base^exponent
     */
    public static double power(double base, int exponent) {
        // Base case: anything raised to the power of 0 is 1

        // Handle negative exponent: a^-n = 1 / (a^n)
        if (exponent < 0) {
            return 1.0 / power(base, -exponent);
        }

        // Base cases
        if (exponent == 0) {
            return 1;
            return 1.0;
        }
        if (exponent == 1) {
            return base;
        }

        // Exponentiation by Squaring
        // If exponent is even: a^n = (a^(n/2))^2
        if (exponent % 2 == 0) {
            double half = power(base, exponent / 2);
            return half * half;
        }

        // Recursive case: base ^ exponent = base * base ^ (exponent - 1)
        // Recurse with a smaller exponent and multiply with base
        // If exponent is odd: a^n = a * a^(n-1)
        return base * power(base, exponent - 1);
    }
 }
diff --git a/src/test/java/com/thealgorithms/maths/PowerUsingRecursionTest.java b/src/test/java/com/thealgorithms/maths/PowerUsingRecursionTest.java

 /**
 * Test case for Power using Recursion
 * @authorBama Charan Chhandogi(https://github.com/BamaCharanChhandogi)
 * @authorVinayak(https://github.com/Vinayak-v12)
 */

 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));
        // exponent = 0
        assertEquals(1.0, PowerUsingRecursion.power(5.0, 0));

        // exponent = 1
        assertEquals(5.0, PowerUsingRecursion.power(5.0, 1));

        // negative exponent
        assertEquals(0.25, PowerUsingRecursion.power(2.0, -2));

        // another negative exponent
        assertEquals(0.5, PowerUsingRecursion.power(2.0, -1));
    }
 }
Original file line number	Diff line number	Diff line change
Expand Up		@@ -2,21 +2,43 @@

		/**
		* calculate Power using Recursion
		* @authorBama Charan Chhandogi(https://github.com/BamaCharanChhandogi)
		* @authorVinayak(https://github.com/Vinayak-v12)
		*/

		public final class PowerUsingRecursion {
		private PowerUsingRecursion() {
		}

		/**
		* Computes base raised to the given exponent.
		*
		* @param base the number to be raised
		* @param exponent the power (can be negative)
		* @return base^exponent
		*/
		public static double power(double base, int exponent) {
		// Base case: anything raised to the power of 0 is 1

		// Handle negative exponent: a^-n = 1 / (a^n)
		if (exponent < 0) {
		return 1.0 / power(base, -exponent);
		}

		// Base cases
		if (exponent == 0) {
		return 1;
		return 1.0;
		}
		if (exponent == 1) {
		return base;
		}

		// Exponentiation by Squaring
		// If exponent is even: a^n = (a^(n/2))^2
		if (exponent % 2 == 0) {
		double half = power(base, exponent / 2);
		return half * half;
		}

		// Recursive case: base ^ exponent = base * base ^ (exponent - 1)
		// Recurse with a smaller exponent and multiply with base
		// If exponent is odd: a^n = a * a^(n-1)
		return base * power(base, exponent - 1);
		}
		}
Original file line number	Diff line number	Diff line change
Expand Up		@@ -6,15 +6,23 @@

		/**
		* Test case for Power using Recursion
		* @authorBama Charan Chhandogi(https://github.com/BamaCharanChhandogi)
		* @authorVinayak(https://github.com/Vinayak-v12)
		*/

		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));
		// exponent = 0
		assertEquals(1.0, PowerUsingRecursion.power(5.0, 0));

		// exponent = 1
		assertEquals(5.0, PowerUsingRecursion.power(5.0, 1));

		// negative exponent
		assertEquals(0.25, PowerUsingRecursion.power(2.0, -2));

		// another negative exponent
		assertEquals(0.5, PowerUsingRecursion.power(2.0, -1));
		}
		}