This commit is contained in:
Aly 2019-12-05 22:11:56 -08:00 committed by Anthony Cerruti
parent abf2060411
commit 4047fc52ac
4 changed files with 81 additions and 1 deletions

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@ -17,7 +17,11 @@ object Main {
val part = askForPart(day)
println("Problem input? End input with an `End of Input` line.")
val input = LazyList.continually(StdIn.readLine()).takeWhile(_ != "End of Input").toList.mkString("\n")
println(s"Output: ${part(input)}")
val startTime = System.currentTimeMillis()
val output = part(input)
val endTime = System.currentTimeMillis()
println(s"Output: $output")
println(s"Time: ${endTime - startTime}ms")
}
def askForYear(): Year = {

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@ -0,0 +1,74 @@
package aoc.y2019
import aoc.Day
import cats._
import cats.implicits._
import cats.data._
import cats.free._
import scala.annotation.tailrec
object Day06 extends Day {
case class Body(name: String)
type Orbits = Cofree[Vector, Body]
import fastparse._, SingleLineWhitespace._
def parseBody[_: P]: P[Body] = P(CharIn("A-Z", "0-9").rep.!).map(Body)
def parseOrbit[_: P]: P[(Body, Body)] = P(parseBody ~ ")" ~ parseBody)
def parseOrbitList[_: P]: P[Vector[(Body, Body)]] = P(parseOrbit.rep(1, "\n")).map(_.toVector)
def constructOrbits(orbitMap: Map[Body, Vector[Body]], initial: Body): Orbits = {
lazy val childOrbits = orbitMap.getOrElse(initial, Vector.empty[Body]).map(constructOrbits(orbitMap, _))
Cofree(initial, Eval.later(childOrbits))
}
def indirectOrbits(orbits: Orbits, level: Int = 0): Int = {
val childOrbits = orbits.tail.value.map(indirectOrbits(_, level + 1))
childOrbits.sum + level
}
def hasBody(orbits: Orbits, body: Body): Boolean = {
orbits.head == body || orbits.tail.value.exists(hasBody(_, body))
}
@tailrec def closestCommonOrbit(orbits: Orbits, a: Body, b: Body): Option[Orbits] = {
def bothChildren(orbits: Orbits): Option[Orbits] = Option.when(hasBody(orbits, a) && hasBody(orbits, b))(orbits)
orbits.tail.value.collectFirstSome(bothChildren) match {
case Some(closerCommonOrbit) => closestCommonOrbit(closerCommonOrbit, a, b)
case None => bothChildren(orbits)
}
}
def distanceToChildBody(orbits: Orbits, target: Body, depth: Int = 0): Option[Int] = {
if(orbits.head == target) depth.some
else orbits.tail.value match {
case Vector() => None
case nonEmpty => nonEmpty.map(distanceToChildBody(_, target, depth + 1)).find(_.isDefined).flatten
}
}
def orbitsFromInput(input: String): Orbits = {
val orbitList = parse(input, parseOrbitList(_)).get.value
val orbitMap = orbitList.groupBy(_._1).view.mapValues(_.map(_._2)).toMap
val firstPlanet = orbitMap.keys.find(body => orbitMap.values.count(_.contains(body)) == 0).get
constructOrbits(orbitMap, firstPlanet)
}
override def part1(input: String): String = {
indirectOrbits(orbitsFromInput(input)).toString
}
override def part2(input: String): String = {
val orbits = orbitsFromInput(input)
val orbitalTransfers = (for {
closestCommon <- closestCommonOrbit(orbits, Body("YOU"), Body("SAN"))
distanceToMe <- distanceToChildBody(closestCommon, Body("YOU"))
distanceToSan <- distanceToChildBody(closestCommon, Body("SAN"))
} yield (distanceToMe + distanceToSan) - 2).get
orbitalTransfers.toString
}
}

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@ -8,6 +8,7 @@ package object y2019 extends Year {
"3" -> Day03,
"4" -> Day04,
"5" -> Day05,
"6" -> Day06,
)
}

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@ -9,6 +9,7 @@ val sharedSettings = Seq(
"com.lihaoyi" %%% "fastparse" % "2.1.3",
"org.scala-graph" %%% "graph-core" % "1.13.1",
"org.typelevel" %%% "cats-core" % "2.0.0",
"org.typelevel" %%% "cats-free" % "2.0.0",
),
mainClass := Some("tf.bug.aoc.Main"),
)