FairWarning.scala

object FairWarning extends App {

  def minSec(seconds: Seq[BigInt]): BigInt = {
    val gcd = seconds.map(_ - seconds.min).reduce(_ gcd _)
    val r = seconds.head % gcd
    if (r == 0) 0 else gcd - r
  }

  def process(lineIn: Iterator[String])(lineOut: String => Unit) =
    for (i <- 1 to lineIn.next().toInt) {
      val line = lineIn.next()
      val seconds = (line split ' ').tail.map(BigInt(_))
      lineOut(s"Case #$i: ${minSec(seconds)}")
    }

  val writer = new java.io.PrintWriter("b.large.out")
  try {
    process(io.Source.fromFile("B-large-practice.in").getLines) { s =>
      writer.println(s)
      writer.flush()
    }
  } finally {
    writer.flush(); writer.close()
  }

}

FairWarningTest.scala

import org.scalatest._

import FairWarning._

class FairWarningTest extends FunSuite {

  test("sample #1") {
    assert(minSec(Seq(26000000, 11000000, 6000000)) === 4000000)
  }

  test("sample #2") {
    assert(minSec(Seq(1, 10, 11)) === 0)
  }

  test("sample #3") {
    assert(minSec(Seq(BigInt("800000000000000000001"), BigInt("900000000000000000001"))) === BigInt("99999999999999999999"))
  }

  test("sample case") {
    val input = """3
3 26000000 11000000 6000000
3 1 10 11
2 800000000000000000001 900000000000000000001""".lines

    val expected = """Case #1: 4000000
Case #2: 0
Case #3: 99999999999999999999""".lines

    lineComparison(input, expected)
  }

  test("full small case") {
    val input = io.Source.fromFile("B-small-practice.in").getLines()
    val expected = io.Source.fromFile("b.small.out.ref").getLines()

    lineComparison(input, expected)
  }

  test("full large case") {
    val input = io.Source.fromFile("B-large-practice.in").getLines()
    val expected = io.Source.fromFile("b.large.out.ref").getLines()

    lineComparison(input, expected)
  }
  def lineComparison(input: Iterator[String], expected: Iterator[String]) {
    process(input) { s =>
      for (line <- s.lines) assert(line.trim === expected.next().trim)
    }
    assert(expected.hasNext === false)
  }

}