day13.scala

package day13

import java.io.FileInputStream
import scala.io.StdIn


@main def solve13_1() =
  case class Bus(id: Int, wating: Int)
  def find(id: Int, time: Int): Bus = Bus(id, id - (time % id))

  val in = new FileInputStream("src/example13-1.in")
  System.setIn(in)
  var time = StdIn.readLine().toInt
  val sol = StdIn.readLine().split(",")
    .filterNot(_.equals("x"))
    .map(x => find(x.toInt, time))
    .minBy(_.wating)
  println(sol.id * sol.wating)

// failed to solve
@main def solve13_2() =
  val in = new FileInputStream("src/example13-1.in")
  System.setIn(in)
  var time = StdIn.readLine().toInt
  case class Bus(item: Int, idx: Int)
  val vec = StdIn.readLine().split(",")
    .zipWithIndex
    .map((item, idx) => if item == "x" then Bus(0, idx) else Bus(item.toInt, idx))
    .filterNot(_.item.equals(0))

  val tree = vec(0).item
  val sol = Iterator.from(1).find(i => vec.forall(bus => {
    val src = tree * i
    val target = src + bus.idx
    if target >= bus.item
    then target % bus.item == 0
    else false
  }))
  println(sol.get * tree)