FairWarning.scala

object Main {

  def solve(input:List[BigInt]):BigInt = {

    def gcd(): BigInt = {
      val diffs = input.sliding(2).map(x => (x(0) - x(1)).abs).toList
      diffs.foldLeft(BigInt(0))(_ gcd _)
    }

    val gcdNum = gcd()
    val result = input(0) % gcdNum
    if (BigInt(0) == result) BigInt(0) else gcdNum - result
  }

  def main(args:Array[String]) = {
    val writer = new java.io.PrintWriter("a-large.out")
    try {
      process(io.Source.fromFile("B-large-practice.in").getLines)(writer.println)
    } finally {
      writer.flush()
      writer.close()
    }
  }

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