BattleshipsClient.scala

import java.net._
import java.io._
import scala.io._

object BattleshipsClient extends App {

  val s = new Socket(InetAddress.getByName("localhost"), 8000)
  lazy val in = new BufferedSource(s.getInputStream()).getLines()
  val out = new PrintStream(s.getOutputStream())

  out.println("0,1")
  out.flush()
  println("Received: " + in.next())

  s.close()

}

BattleshipsServer.scala

import java.net._
import java.io._
import scala.io._

object BattleshipsServer extends App {

  val initState = List(
    List(0, 1, 0),
    List(0, 0, 1),
    List(0, 0, 0)
  )

  val server = new ServerSocket(8000)

  def respond(s: String, currentState: List[List[Int]]) = {
    val x: Int = s.split(",")(0).toInt
    val y: Int = s.split(",")(1).toInt
    (currentState(x)(y), x, y)
  }

  def nextIteration(state: List[List[Int]]) {
    val s = server.accept()
    val in = new BufferedSource(s.getInputStream()).getLines()
    val out = new PrintStream(s.getOutputStream())

    val response: (Int, Int, Int) = respond(in.next(), state)
    out.println(response._1)
    val newState: List[List[Int]] = for (i <- (0 until state.length).toList) yield {
      for (j <- (0 until state(0).length).toList) yield {
        if (i == response._2 && j == response._3 && response._1 == 1) -1
        else state(i)(j)
      }
    }

    out.flush()
    s.close()

    nextIteration(newState)
  }

  nextIteration(initState)

}