add power

realDuYuanChao · realDuYuanChao · commit 4dabd5331924 · 2020-10-05T11:37:37.000+08:00
diff --git a/src/main/java/com/examplehub/maths/Power.java b/src/main/java/com/examplehub/maths/Power.java
@@ -0,0 +1,19 @@
+package com.examplehub.maths;
+
+public class Power {
+
+    /**
+     * 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) {
+        int power = 1;
+        for (int i = 1; i <= b; i++) {
+            power *= a;
+        }
+        return power;
+    }
+}
diff --git a/src/main/java/com/examplehub/maths/PowerRecursion.java b/src/main/java/com/examplehub/maths/PowerRecursion.java
@@ -0,0 +1,15 @@
+package com.examplehub.maths;
+
+public class PowerRecursion {
+
+    /**
+     * Returns the value of the first argument raised to the power of the second argument using recursion.
+     *
+     * @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);
+    }
+}
diff --git a/src/test/java/com/examplehub/maths/PowerRecursionTest.java b/src/test/java/com/examplehub/maths/PowerRecursionTest.java
@@ -0,0 +1,19 @@
+package com.examplehub.maths;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class PowerRecursionTest {
+
+    @Test
+    void testPow() {
+        assertEquals(1, PowerRecursion.pow(0, 0));
+        assertEquals(0, PowerRecursion.pow(0, 10));
+        assertEquals(1, PowerRecursion.pow(1, 0));
+        assertEquals(2, PowerRecursion.pow(2, 1));
+        assertEquals(8, PowerRecursion.pow(2, 3));
+        assertEquals(1024, PowerRecursion.pow(2, 10));
+        assertEquals(625, PowerRecursion.pow(25, 2));
+    }
+}
diff --git a/src/test/java/com/examplehub/maths/PowerTest.java b/src/test/java/com/examplehub/maths/PowerTest.java
@@ -0,0 +1,19 @@
+package com.examplehub.maths;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class PowerTest {
+
+    @Test
+    void testPow() {
+        assertEquals(1, Power.pow(0, 0));
+        assertEquals(0, Power.pow(0, 10));
+        assertEquals(1, Power.pow(1, 0));
+        assertEquals(2, Power.pow(2, 1));
+        assertEquals(8, Power.pow(2, 3));
+        assertEquals(1024, Power.pow(2, 10));
+        assertEquals(625, Power.pow(25, 2));
+    }
+}
