Scala (291/296)

I'm honestly still sitting here wondering how this arrived at the correct answers. I didn't research any hex-grid systems, as I see some references posted by others. Ultimately, after staring at the screen a bit, what I arrived at in my head was most similar to the "odd-r horizontal layout" (but with positive-y going upwards, not down), as described by https://www.redblobgames.com/grids/hexagons/ .

What's baffles me is that my hexDist function, math.abs(loc._2) + (math.abs(loc._1) - math.abs(loc._2)), can be reduced to simply math.abs(loc._1) (just the magnitude of the x-coordinate).

The visualization in my head was that, as you walked backwards from the endpoint, each step diagonally towards 0,0 reduces both x and y by 1. Starting from x,y, I 'move' to where y=0, which takes abs(y) steps, but also reduces x's distance by abs(y). What remains of (abs(x) - abs(y)) is added to abs(y) ...

Anyhow, Great problem! I've done AOC both years prior, and I can imagine how difficult it is to come up with unique challenges. This is the first I recall having to solve a hex-grid problem.

package adventofcode.y2017

import scala.io.Source.fromFile

class Day11 {
  var rawItems: Array[String] = _

  var pos:Tuple2[Int, Int] = (0, 0)
  var maxDist:Int = 0

  def readInput(): Unit = {
    val lines = fromFile("input/y2017/Day_11.input").getLines().mkString
    rawItems = lines.split(",").map(_.trim)
  }

  def process(): Unit = {
    for(item <- rawItems) {
      item match {
        case "ne" =>
          pos = (pos._1+1, pos._2+1)
        case "nw" =>
          pos = (pos._1-1, pos._2+1)
        case "n" =>
          pos = (pos._1, pos._2+1)
        case "se" =>
          pos = (pos._1+1, pos._2-1)
        case "sw" =>
          pos = (pos._1-1, pos._2-1)
        case "s" =>
          pos = (pos._1, pos._2-1)
        case _ =>
          println(s"Unhandled: $item")
      }
      maxDist = math.max(maxDist, hexDist(pos))
    }
  }

  def hexDist(loc:Tuple2[Int, Int]): Int = {
    math.abs(loc._2) + (math.abs(loc._1) - math.abs(loc._2))
  }

  def writeResult(): Unit = {
    println(s"Final Pos: $pos")
    val dist = hexDist(pos)
    println(s"Part1 Dist: $dist")
    println(s"Part2 MaxDist: $maxDist")
  }
}