An answer of http://nabetani.sakura.ne.jp/hena/ord30taxi/

taxi.scala

trait FareChart {
  def baseFare: Int 

  def baseDistance: Int 

  def extraFare: Int 
}

class EnraiFareChart extends FareChart {
  def baseFare: Int = 400 

  def baseDistance: Int = 995 

  def extraFare: Int = 60
}

class TansuFareChart extends FareChart {
  def baseFare: Int = 350 

  def baseDistance: Int = 845 

  def extraFare: Int = 50
}

class FareChartFactory {
  def create(s: String): FareChart = { 
    s match {
      case "A" | "B" | "C" | "AB" | "AC" | "BC" | "CF" | "BG"=>
        new EnraiFareChart()
      case _ =>
        new TansuFareChart()
    }   
  }
}

object Distance {
  def between(from: String, to: String): Int = {
    val interval = Array(from, to).sorted.mkString
    interval match {
      case "AB" => 1090
      case "AC" => 180
      case "AD" => 540
      case "BC" => 960
      case "BG" => 1270
      case "CD" => 400
      case "CF" => 200
      case "DE" => 720
      case "DF" => 510
      case "EG" => 1050
      case "FG" => 230
    }
  }
}

class Taxi {
  def calculateFare(route: String): Int = {
    val chart = (new FareChartFactory).create(route.substring(0, 1))
    calculateFareImpl(route, chart.baseFare, chart.baseDistance)
  }

  private val BaseDistance = 200

  @scala.annotation.tailrec
  private def calculateFareImpl(route: String, fare: Int, distance: Int): Int = {
    if(route.length == 1) {
      return fare
    }
    val (from, to) = (route.substring(0, 1), route.substring(1, 2))
    val runningDistance = Distance.between(from, to)
    if(isMeterClicked(distance, runningDistance)) {
      val chart = (new FareChartFactory).create(Array(from, to).sorted.mkString)
      val counts = meterClickedCount(distance, runningDistance)
      val curDist = BaseDistance - (runningDistance - distance) % BaseDistance
      calculateFareImpl(route.drop(1), fare + chart.extraFare * counts, curDist)
    } else {
      calculateFareImpl(route.drop(1), fare, distance - runningDistance)
    }
  }

  private def isMeterClicked(meterClickedDistance: Int, runningDistance: Int): Boolean =
    meterClickedDistance < runningDistance

  private def meterClickedCount(meterClickedDistance: Int, runningDistance: Int): Int =
      (runningDistance - meterClickedDistance) / BaseDistance + 1
}

class Solver {
  def main(args: Array[String]) {
    testAll
  }

  def test(src: String, expected: String) {
    val actual = (new Taxi).calculateFare(src).toString
    actual match {
      case `expected` => println("ok")
      case _ => println("***NG***")
    }
  }

  def testAll {
    /*0*/ test( "ADFC", "510" )
    /*1*/ test( "CFDA", "500" )
    /*2*/ test( "AB", "460" )
    /*3*/ test( "BA", "460" )
    /*4*/ test( "CD", "400" )
    /*5*/ test( "DC", "350" )
    /*6*/ test( "BG", "520" )
    /*7*/ test( "GB", "530" )
    /*8*/ test( "FDA", "450" )
    /*9*/ test( "ADF", "450" )
    /*10*/ test( "FDACB", "750" )
    /*11*/ test( "BCADF", "710" )
    /*12*/ test( "EDACB", "800" )
    /*13*/ test( "BCADE", "810" )
    /*14*/ test( "EGFCADE", "920" )
    /*15*/ test( "EDACFGE", "910" )
    /*16*/ test( "ABCDA", "960" )
    /*17*/ test( "ADCBA", "1000" )
    /*18*/ test( "BADCFGB", "1180" )
    /*19*/ test( "BGFCDAB", "1180" )
    /*20*/ test( "CDFC", "460" )
    /*21*/ test( "CFDC", "450" )
    /*22*/ test( "ABGEDA", "1420" )
    /*23*/ test( "ADEGBA", "1470" )
    /*24*/ test( "CFGB", "640" )
    /*25*/ test( "BGFC", "630" )
    /*26*/ test( "ABGEDFC", "1480" )
    /*27*/ test( "CFDEGBA", "1520" )
    /*28*/ test( "CDFGEDABG", "1770" )
    /*29*/ test( "GBADEGFDC", "1680" )
  }
}