object ReverseSentence extends App {
  if (args == null || args.length == 0) {
    printf("%d arguments found; 2 arguments required.", Option(args).map(_.length).getOrElse(0))
    sys.exit(0);
  }

  if (args(0) == args(1)) {
    println("The string parameters are equal.")
    sys.exit(0)
  }
  var str = args(0).toCharArray();
  val goal = args(1).toCharArray();

  println("Original: '" + new String(str) + "'");

  reverse(str);

  val success = new String(str).equals(new String(goal));
  println("Reversed: '" + new String(str) + "'\n\nReverse "
          + (if (success) "succeeded." else "failed!"));

  def reverse(s: Array[Char]): Unit = {
    var str = "";
    var newWord = "";

    for (i <- (s.length - 1) to 0 by -1) {
      val char = s(i);

      if (char != ' ') {
        newWord = char + newWord;
      } else {
        str += newWord + char;
        newWord = "";
      }
    }
    str += newWord;

    for (i <- 0 until s.length) {
      s(i) = str.charAt(i);
    }
  }
}