Added Ackermann function (#794)

* Ackermann added.

* Ackermann updated

src/main/java/com/others/Ackermann.java

@@ -0,0 +1,34 @@
+package src.main.java.com.others;
+
+
+public class Ackermann {
+
+
+  /**
+   * Ackermann function - simplest and earliest-discovered examples of a total computable function
+   * that is not primitive recursive.
+   * 
+   * Defined only for NONNEGATIVE integers !!!
+   * 
+   * Time complexity is super-exponential. O(n(^))
+   * Any input m higher tahn (3,3) will result in StackOverflow
+   * @param m
+   * @param n
+   * @return
+   *
+   *
+   */
+  public long Ack(long m, long n) {
+
+    if (m == 0)
+      return n + 1;
+
+    if (n == 0)
+      return Ack(m - 1, 1);
+
+    return Ack(m - 1, Ack(m, n - 1));
+  }
+
+}
+
+

src/test/java/com/others/AckermannTest.java

@@ -0,0 +1,19 @@
+package src.test.java.com.others;
+
+import src.main.java.com.others.Ackermann;
+import static org.junit.Assert.assertEquals;
+import org.junit.Test;
+
+public class AckermannTest {
+
+  @Test
+  public void testAckermann() {
+    Ackermann ackTest = new Ackermann();
+    assertEquals("Error", 1, ackTest.Ack(0, 0));
+    assertEquals("Error", 3, ackTest.Ack(1, 1));
+    assertEquals("Error", 7, ackTest.Ack(2, 2));
+  }
+
+
+
+}