Sorting.scala

object Sorting extends App {

  def sort(s: Int*): Seq[Int] = {
    val odds = s.filter(_ % 2 != 0).toList
    val even = s.filter(_ % 2 == 0).toList
    val mask = s.map(_ % 2 != 0).toList
    merge(odds.sorted, even.sorted.reverse, mask)
  }

  @annotation.tailrec
  def merge(odds: List[Int], even: List[Int], mask: List[Boolean], acc: List[Int] = Nil): List[Int] =
    if (mask.isEmpty) acc.reverse
    else {
      val (odds0, even0, current) =
        if (mask.head) (odds.tail, even, odds.head) else (odds, even.tail, even.head)
      merge(odds0, even0, mask.tail, current :: acc)
    }

  def process(lineIn: Iterator[String])(lineOut: String => Unit) =
    for (i <- 1 to lineIn.next().toInt) {
      val n = lineIn.next()
      val ss = lineIn.next().split(' ').map(_.toInt)

      lineOut(s"Case #$i: ${sort(ss: _*) mkString " "}")
    }

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

}

SortingTest.scala

import org.scalatest._

import Sorting._

class SortingTest extends FunSuite {

  test("sample #1") {
    assert(sort(5, 2, 4, 3, 1) === Seq(1, 4, 2, 3, 5))
  }

  test("sample #2") {
    assert(sort(-5,-12, 87, 2, 88, 20, 11) === Seq(-5, 88, 11, 20, 2, -12, 87))
  }

  test("sample case") {
    val input = """2
5
5 2 4 3 1
7
-5 -12 87 2 88 20 11""".lines

    val expected = """Case #1: 1 4 2 3 5
Case #2: -5 88 11 20 2 -12 87""".lines

    process(input) { s =>
      assert(s === expected.next())
    }
  }

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

    process(input) { s =>
      assert(s === expected.next())
    }
  }
  
  
  test("full large case") {
    val input = io.Source.fromFile("C-large-practice.in").getLines()
    val expected = io.Source.fromFile("c.large.out.ref").getLines()

    process(input) { s =>
      assert(s === expected.next())
    }
  }

}