Battleship.scala

import java.io.PrintWriter

import scala.io.Source

class Battleship {

  def lines = Source.fromFile("large.in").getLines.toList.tail

  val writer = new PrintWriter("large.out")

  def run: Unit = {

    lines.map(solve).zipWithIndex.foreach({ case (r, i) => writer.println("Case #" + (i + 1) + ": " + r) })

    writer.flush()
    writer.close()
  }

  def solve(s: String): Long = {
    val Array(r, c, w) = s.split(" ").map(_.toLong)
    if (c % w == 0)
      r * (c / w) + (w - 1)
    else
      r * (c / w) + w
  }

}

BattleshipTest.scala

import org.scalatest.FunSuite

class BattleshipTest extends FunSuite {

  val battleship = new Battleship

  test("1") {

    assert("1 4 2" === battleship.lines.head)

  }

  test("2") {

    assert(3 === battleship.solve("1 4 2"))
    assert(7 === battleship.solve("1 7 7"))
    assert(10 === battleship.solve("2 5 1"))

  }

  test("print") {

    battleship.run;

  }

}