2022-day5.scala

import scala.io.Source

def input2Stack(input: List[String]): List[String] =
  input.transpose.filter(xs => xs.head != ' ').map(_.mkString.trim())
  
def sperateInput(input: List[String], res: List[String]): (List[String], List[String]) =
  val (x :: xs) = input
  if x == "" then return (res, xs)
  sperateInput(xs, x :: res)

def runCommands(commands: List[String], origin: List[String], cnt: Int, fn: (String, List[String]) => List[String]): List[String] =
  if commands.length == cnt then return origin
  runCommands(commands, fn(commands(cnt), origin), cnt + 1, fn)
  
val commandReg = raw"move (\d+) from (\d+) to (\d+)".r

def runCommand(input: String, origin: List[String]): List[String] =
  def inner(from: Int, to: Int, cnt: Int): List[String] =
    val fromTxt = origin(from).dropRight(cnt)
    val toTxt = origin(to) + origin(from).takeRight(cnt).reverse
    origin.updated(from, fromTxt).updated(to, toTxt)

  input match
    case commandReg(cnt, from, to) => inner(from.toInt - 1, to.toInt - 1, cnt.toInt)

def runCommand2(input: String, origin: List[String]): List[String] =
  def inner(from: Int, to: Int, cnt: Int): List[String] =
    val fromTxt = origin(from).dropRight(cnt)
    val toTxt = origin(to) + origin(from).takeRight(cnt)
    origin.updated(from, fromTxt).updated(to, toTxt)

  input match
    case commandReg(cnt, from, to) => inner(from.toInt - 1, to.toInt - 1, cnt.toInt)

def ans1(xs: List[String]): String =
  val (firstInput, secondInput) = sperateInput(xs, Nil)
  val stacks = input2Stack(firstInput)
  val result = runCommands(secondInput, stacks, 0, runCommand)
  result.map(_.takeRight(1)).mkString

def ans2(xs: List[String]): String =
  val (firstInput, secondInput) = sperateInput(xs, Nil)
  val stacks = input2Stack(firstInput)
  val result = runCommands(secondInput, stacks, 0, runCommand2)
  result.map(_.takeRight(1)).mkString

def solve =
  val input = Source.fromFile("day5.txt").getLines.toList
  println(ans1(input))
  println(ans2(input))