SudokuChecker.scala

object SudokuChecker extends App {

  def check(matrix: Vector[Vector[Int]]): Boolean = {

    val nSq = matrix.size
    val n = math.sqrt(nSq).toInt
    val ans = (1 to nSq).toSet

    (0 until nSq).forall { i: Int =>

      (for (i1 <- 0 until n; j1 <- 0 until n)
        yield matrix(i1 + n * (i / n))(j1 + n * (i % n))).toSet == ans &&
        matrix(i).toSet == ans &&
        (Set.empty[Int] /: matrix)(_ + _(i)) == ans

    }
  }

  def process(lineIn: Iterator[String])(lineOut: String => Unit) =
    for (i <- 1 to lineIn.next().toInt) {
      val n = lineIn.next().toInt
      val m = Vector.fill(n * n)(lineIn.next().split(' ').map(_.toInt).toVector)
      lineOut(s"Case #$i: ${if (check(m)) "Yes" else "No"}")
    }

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

}

SudokuCheckerTest.scala

import org.scalatest._

import SudokuChecker._

class SudokuCheckerTest extends FunSuite {

  import language.implicitConversions
  implicit def linesToMatrix(lines: String): Vector[Vector[Int]] =
    lines.lines.toVector.map(_.split(' ').map(_.toInt).toVector)

  test("sample #1") {
    val m = """5 3 4 6 7 8 9 1 2
6 7 2 1 9 5 3 4 8
1 9 8 3 4 2 5 6 7
8 5 9 7 6 1 4 2 3
4 2 6 8 5 3 7 9 1
7 1 3 9 2 4 8 5 6
9 6 1 5 3 7 2 8 4
2 8 7 4 1 9 6 3 5
3 4 5 2 8 6 1 7 9"""

    assert(check(m) === true)
  }

  test("sample #2") {
    val m = """1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9"""

    assert(check(m) === false)
  }

  test("sample #3") {
    val m = """5 3 4 6 7 8 9 1 2
6 7 2 1 9 5 3 4 8
1 9 8 3 4 2 5 6 7
8 5 9 7 6 1 4 2 3
4 2 6 8 999 3 7 9 1
7 1 3 9 2 4 8 5 6
9 6 1 5 3 7 2 8 4
2 8 7 4 1 9 6 3 5
3 4 5 2 8 6 1 7 9"""

    assert(check(m) === false)
  }
  test("sample case") {
    val input = """3
3
5 3 4 6 7 8 9 1 2
6 7 2 1 9 5 3 4 8
1 9 8 3 4 2 5 6 7
8 5 9 7 6 1 4 2 3
4 2 6 8 5 3 7 9 1
7 1 3 9 2 4 8 5 6
9 6 1 5 3 7 2 8 4
2 8 7 4 1 9 6 3 5
3 4 5 2 8 6 1 7 9
3
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
3
5 3 4 6 7 8 9 1 2
6 7 2 1 9 5 3 4 8
1 9 8 3 4 2 5 6 7
8 5 9 7 6 1 4 2 3
4 2 6 8 999 3 7 9 1
7 1 3 9 2 4 8 5 6
9 6 1 5 3 7 2 8 4
2 8 7 4 1 9 6 3 5
3 4 5 2 8 6 1 7 9""".lines

    val expected = """Case #1: Yes
Case #2: No
Case #3: No""".lines

    process(input) { s =>
      for (line <- s.lines)
        assert(line === expected.next())
    }
  }

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

    process(input) { s =>
      for (line <- s.lines)
        assert(line === expected.next())
    }
  }

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

    process(input) { s =>
      for (line <- s.lines)
        assert(line === expected.next())
    }
  }

}