Add naive calculation of Fibonacci numbers

anverbogatov · anverbogatov · commit 04a46c302c9c · 2022-03-09T20:36:58.000+04:00
diff --git a/src/main/java/com/anverbogatov/algorithms/calculations/FibonacciNumbers.java b/src/main/java/com/anverbogatov/algorithms/calculations/FibonacciNumbers.java
@@ -0,0 +1,22 @@
+package com.anverbogatov.algorithms.calculations;
+
+public final class FibonacciNumbers {
+
+    /**
+     * Naive implementation of Fibonnacci numbers calculation.
+     * Recursion-based approach.
+     * Complexity is O(2^n).
+     *
+     * @param n - starting number
+     * @return sum of Fibonnaci numbers
+     */
+    public static int calculate(int n) {
+        if (n == 0) {
+            return 0;
+        }
+        if (n == 1) {
+            return 1;
+        }
+        return calculate(n - 1) + calculate(n - 2);
+    }
+}
diff --git a/src/test/java/com/anverbogatov/algorithms/calculations/FibonacciNumbersTest.java b/src/test/java/com/anverbogatov/algorithms/calculations/FibonacciNumbersTest.java
@@ -0,0 +1,19 @@
+package com.anverbogatov.algorithms.calculations;
+
+import junit.framework.TestCase;
+import org.junit.Assert;
+
+public class FibonacciNumbersTest extends TestCase {
+
+    public void testCalculateForZero() {
+        Assert.assertEquals(0, FibonacciNumbers.calculate(0));
+    }
+
+    public void testCalculateForOne() {
+        Assert.assertEquals(1, FibonacciNumbers.calculate(1));
+    }
+
+    public void testCalculate() {
+        Assert.assertEquals(3524578, FibonacciNumbers.calculate(33));
+    }
+}
