BotTrust.scala

object BotTrust extends App {
  def line2list(line: String): List[(Char, Int)] = {
    val itemList = line.split(" ").tail.toList
    (for (i <- 0 until (itemList.size / 2)) yield (itemList(2 * i)(0), itemList(2 * i + 1).toInt)).toList
  }                                               //> line2list: (line: String)List[(Char, Int)]

  def getTarget(list: List[(Char, Int)]): (Int, Int) = {
    val oTarget = list.find(item => item._1 == 'O') match {
      case None => -1
      case Some(num) => num._2
    }

    val bTarget = list.find(item => item._1 == 'B') match {
      case None => -1
      case Some(num) => num._2
    }

    (oTarget, bTarget)
  }                                               //> getTarget: (list: List[(Char, Int)])(Int, Int)
  
  def getTurn(list: List[(Char, Int)]): Char = list match {
    case Nil => -1.toChar
    case head :: tail => head._1
  }                                               //> getTurn: (list: List[(Char, Int)])Char
  
  def simulate(list: List[(Char, Int)], oPos: Int, bPos: Int, tic: Int): Int = {
    if (list.isEmpty) tic
    else {
      val (oTrg, bTrg) = getTarget(list)
      val turn = getTurn(list)

      var nextOPos = oPos
      var nextBPos = bPos
      var nextList = list

      if (oTrg == oPos) {
        if (turn == 'O') {
          // push
          nextList = list.tail
        } else {
          // stay, already on button
        }
      } else if (oTrg == -1) {
        // stay, no more button to push
      } else {
        // move
        nextOPos = if (oTrg > oPos) (oPos + 1) else (oPos - 1)
      }

      if (bTrg == bPos) {
        if (turn == 'B') {
          // push
          nextList = list.tail
        } else {
          // stay, already on button
        }
      } else if (bTrg == -1) {
        // stay, no more button to push
      } else {
        // move
        nextBPos = if (bTrg > bPos) (bPos + 1) else (bPos - 1)
      }

      simulate(nextList, nextOPos, nextBPos, tic + 1)
    }
  }                                               //> simulate: (list: List[(Char, Int)], oPos: Int, bPos: Int, tic: Int)Int
  
  def solve(line: String): Int = simulate(line2list(line), 1, 1, 0)
                                                  //> solve: (line: String)Int

  //////////
  // main //
  //////////
    if (args.length > 0) Console.setIn(new java.io.FileInputStream(args(0)))
    if (args.length > 1) Console.setOut(new java.io.FileOutputStream(args(1)))

    for (t <- 1 to readInt) {
      val line = readLine
      println("Case #%d: %d".format(t, solve(line)))
    }
}