RankAndFile.scala

package com.jayden

/**
  * Created by jaydenuk on 2016. 7. 29..
  */
object RankAndFileMain extends App{


  def missingList(l: Seq[Seq[Int]]): Seq[Int] =
    l.flatten.groupBy(identity).mapValues(_.size).filter{case (k, v) => v % 2 > 0}.keySet.toSeq.sorted

  def process(lines: Iterator[String])(writer: java.io.PrintWriter) = for(i <- 1 to lines.next().toInt) {
    val n = lines.next().toInt
    val ans = missingList(Seq.fill(2*n-1){lines.next().split(" ").map(_.toInt).toList})
    writer.println(s"Case #$i: ${ans mkString " "}")
  }

  val filename = "B-large-practice"
  val writer = new java.io.PrintWriter(filename + ".out")

  try {
    process(io.Source.fromFile(filename + ".in").getLines)(writer)
  } finally {
    writer.flush(); writer.close()
  }
}