fibonacci algorithm

Author: melmedany

src/main/java/FibonacciNumbers.java

@@ -0,0 +1,37 @@
+import java.math.BigInteger;
+
+/**
+ * @author medany
+ */
+
+public class FibonacciNumbers {
+	public BigInteger solve(int n) {
+		return fibonacci(n);
+	}
+
+	public BigInteger solveNoRecursion(int n) {
+		return fibonacciNoRecursion(n);
+	}
+
+	private BigInteger fibonacci(int n) {
+		if (n <= 1) {
+			return BigInteger.valueOf(n);
+		}
+		return fibonacci(n - 1).add((fibonacci(n - 2)));
+	}
+
+	private BigInteger fibonacciNoRecursion(int x) {
+		if (x == 0 || x == 1) {
+			return BigInteger.valueOf(x);
+		} else {
+			BigInteger a = BigInteger.ZERO, b = BigInteger.ONE;
+			BigInteger r = BigInteger.ZERO;
+			for (int i = 2; i <= x; i++) {
+				r = a.add(b);
+				a = b;
+				b = r;
+			}
+			return r;
+		}
+	}
+}

test/main/java/FibonacciNumbersTest.java

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+import static org.junit.Assert.assertEquals;
+
+import java.math.BigInteger;
+
+import org.junit.Test;
+
+/**
+ * @author medany
+ */
+
+public class FibonacciNumbersTest {
+
+	@Test
+	public void Test_1() {
+		FibonacciNumbers alg = new FibonacciNumbers();
+
+		BigInteger actual = alg.solve(1), expected = BigInteger.ONE;
+
+		System.out.println(actual);
+		assertEquals(expected, actual);
+	}
+
+	@Test
+	public void Test_2() {
+		FibonacciNumbers alg = new FibonacciNumbers();
+
+		BigInteger actual = alg.solve(5), expected = BigInteger.valueOf(5);
+
+		System.out.println(actual);
+		assertEquals(expected, actual);
+	}
+
+	@Test
+	public void Test_3() {
+		FibonacciNumbers alg = new FibonacciNumbers();
+
+		BigInteger actual = alg.solve(10), expected = BigInteger.valueOf(55);
+
+		System.out.println(actual);
+		assertEquals(expected, actual);
+	}
+
+	@Test
+	public void Test_4() {
+		FibonacciNumbers alg = new FibonacciNumbers();
+
+		BigInteger actual = alg.solveNoRecursion(1000);
+		BigInteger expected = new BigInteger(
+				"43466557686937456435688527675040625802564660517371780402481729089536555417949051890403879840079255169295922593080322634775209689623239873322471161642996440906533187938298969649928516003704476137795166849228875");
+
+		System.out.println(actual);
+		assertEquals(expected, actual);
+	}
+}