import java.util.Random;

public class Test {

  private static final int NUMBER_OF_ITERATIONS = 90000000;
  private static final int NUMBER_OF_TEST_EXECUTIONS = 50;

  static double multiply_by_power_of_ten(final double d, final int exponent) {
    switch (exponent) {
      case  0: return d;
      case  1: return d * 10;
      case  2: return d * 100;
      case  3: return d * 1000;
      case  4: return d * 10000;
      case  5: return d * 100000;
      case  6: return d * 1000000;
      case  7: return d * 10000000;
      case  8: return d * 100000000;
      case  9: return d * 1000000000;
      case 10: return d * 10000000000L;
      case 11: return d * 100000000000L;
      case 12: return d * 1000000000000L;
      case 13: return d * 10000000000000L;
      case 14: return d * 100000000000000L;
      case 15: return d * 1000000000000000L;
      case 16: return d * 10000000000000000L;
      default:
      return 0.0;
    }
  }

  public static void main(String[] argv) {

    double dead = 0.0;
    long overall_time = 0;
    System.out.println("Collecting random values..");

    int[] random_values = new int[NUMBER_OF_ITERATIONS];

    Random rand = new Random();
    for (int i = 0; i < NUMBER_OF_ITERATIONS; ++i) {
      random_values[i] = rand.nextInt(17);
    }

    System.out.println("Running tests..");

    for (int i = 0; i <= NUMBER_OF_TEST_EXECUTIONS; ++i) {
      long start_time = System.nanoTime();

      for (int j = 0; j < NUMBER_OF_ITERATIONS; ++j) {
        dead = multiply_by_power_of_ten(10.0, random_values[j]);
      }

      long end_time = System.nanoTime();
      long test_time = end_time - start_time;

      System.out.print("[" + i + "]: " + test_time);

      if (i == 0) {
        System.out.println(" (ignored)");
      } else {
        overall_time += test_time;
        System.out.println("");
      }
    }

    System.out.println("Test completed. Mean is: " + overall_time / NUMBER_OF_TEST_EXECUTIONS);
    System.out.println("(Ignore value " + dead + ")");
  }
}