README.md

Day 10: Just play the game

Haven't you ever been bored at school?

Santa is in trouble. He's elves are busy playing TicTacToe. Beat them and help Sata to save christmas!

nc challenges.hackvent.hacking-lab.com 1037

Solution

I really enjoyed this one! After beating the game manually I decided to write a Scala program (source code can be found here) which could beat the AI on the other side.

def main(args: Array[String]): Unit = {
  val nc = NetCat.open("challenges.hackvent.hacking-lab.com", 1037)
  try {
    // start game
    nc.read
    nc.writeln("")

    // play game
    var finished = false
    while (!finished) {
      val msg = nc.read
      if (msg.contains("HV17")) {
        println(msg.split('\n').find(_.startsWith("HV17")).get)
        finished = true
      } else if (msg.contains("Congratulations you won!")) {
        println(msg.split('\n').find(_.startsWith("Congratulations")).get)
        nc.writeln("")
      } else if (msg.contains("There is no winner")) {
        println("There is no winner")
        nc.writeln("")
      } else if (msg.endsWith("Field: ")) {
        val field = parseField(msg)
        val move = field match {
          case "*********" => 1
          case "X***O****" => 9
          case "X*O*O***X" => 7
          case "X*O*O*XOX" => 4
          case "XOO*O*X*X" => 4
          case "XO**O***X" => 8
          case "XO*******" => 7
          case "XO**O*OXX" => 3
          case "XOX*OOOXX" => 4
          case "XO*O**X**" => 5
          case "XOO*O**XX" => 7
          case "XO*OX*X*O" => 3
          case "XOXOO*OXX" => 6
          case "XOO***X**" => 4
          case "XOOOX*X**" => 9
          case _ => throw new IllegalArgumentException("Unexpected field: " + field)
        }
        nc.writeln(move.toString)
      }
    }
  } finally {
    nc.close
  }
}

private def parseField(field: String): String = {
  val lines = field.split('\n')
  (11 to 5 by -3).map(i => lines(lines.length - i).replaceAll("[ |]", "")).mkString
}

You will get the flag as a reward for beating the game.

HV17-y0ue-kn0w-7h4t-g4me-sure