Rank and File.scala

package Main

import java.io.{FileInputStream, FileOutputStream}

import scala.annotation.tailrec
import scala.io.StdIn


object Main extends App {
    Console.setIn(new FileInputStream("example.in"))

    Console.setIn(new FileInputStream("B-small-practice.in"))
    Console.setOut(new FileOutputStream("B-small-practice.out"))

    Console.setIn(new FileInputStream("B-large-practice.in"))
    Console.setOut(new FileOutputStream("B-large-practice.out"))

    def solve(inputs:List[List[Int]]): String = {
        inputs.flatten
            .groupBy(x => x)
            .filter{case (_, v) => 1 == v.size % 2}
            .keys
            .toList
            .sorted
            .mkString(" ")
    }

    val cases = StdIn.readLine().toInt
    (1 to cases) foreach { i => {
        val n = StdIn.readInt()
        val inputs = for (x <- 0 until 2 * n - 1) yield StdIn.readLine().split(" ").map(_.toInt).toList
        println(s"Case #$i: ${solve(inputs.toList)}")
    }}
}