Darkus June FP contest solution

Stars.scala

import io.Source

object Stars {
  type Point = Array[Int]
  type Tree = Array[Array[Array[List[Point]]]]

  def main(args:Array[String]) {
    val start:Long = System.nanoTime()
    val coords = Source.fromFile("stars.dat").getLines().map(s => s.split("\\s+").map(_.toInt)).toArray
    var minDistance = Long.MaxValue
    var s1:Point = Array(-1, -1, -1)
    var s2:Point = Array(-1, -1, -1)
    var maxC = 0
    for (c <- coords) {
      for (p <- c) {
        maxC = p max maxC
      }
    }
    val part: Int = 100
    val div = maxC / part
    val tree:Tree = Array.fill(part + 1, part + 1, part + 1)({List.empty[Point]})
    val neighbours = for (x <- Array(-1, 0, 1); y <- Array(-1, 0, 1); z <-Array(-1, 0, 1)) yield (x, y, z)
    for (c <- coords) {
      val i = c(0) / div
      val j = c(1) / div
      val k = c(2) / div
      for (t <- neighbours) {
        val x = t._1 + i
        val y = t._2 + j
        val z = t._3 + k
        if (x >= 0 && x < tree.length && y >= 0 && y < tree.length && z >= 0 && z < tree.length) {
          tree(x)(y)(z) = c :: tree(x)(y)(z)
        }
      }
    }
    for (i <- 0 until tree.length; j <- 0 until tree(i).length; k <- 0 until tree(i)(j).length) {
      val group = tree(i)(j)(k).toArray
      val (localMin, localS1, localS2) = solve(group)
      if (localMin < minDistance) {
        minDistance = localMin
        s1 = localS1
        s2 = localS2
      }
    }
    val total = System.nanoTime() - start
    println("distance " + math.sqrt(minDistance))
    println("A(" + s1.mkString(", ") + ")")
    println("B(" + s2.mkString(", ") + ")")
    println("time elapsed: " + total / 1000000 + " ms")
  }

  def solve(points: Array[Point]):Tuple3[Long, Point, Point] = {
    var min = Long.MaxValue
    var s1:Point = null
    var s2:Point = null
    for (i <- 0 until points.length; j <- (i + 1) until points.length) {
      val d = distance(points(i), points(j))
      if (d < min) {
        min = d
        s1 = points(i)
        s2 = points(j)
      }
    }
    (min, s1, s2)
  }

  def distance(a:Point, b:Point):Long = {
    val dx:Long = a(0) - b(0)
    val dy:Long = a(1) - b(1)
    val dz:Long = a(2) - b(2)
    dx * dx + dy * dy + dz* dz
  }
}

//distance 85.98255637046388
//A(637999, 813818, 458335)
//B(637957, 813791, 458265)
//time elapsed: 78541 ms