70 lines
1.7 KiB
Scala
70 lines
1.7 KiB
Scala
package aoc.day18
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import aoc._
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import aoc.direction._
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import Dir._
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import scala.collection.SortedMap
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import scala.collection.mutable
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case class Dig(dir: Dir, count: Int, color: String):
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lazy val part2 = Parser.parse(Parser.digHex, color).get
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def apply(x: Long, y: Long) = dir.long(x, y, count)
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object Parser extends CommonParser with DirParser:
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val dig = dir ~ num ~ "(#" ~ """[0-9a-f]{6}""".r ~ ")" ^^ { case dir ~ num ~ _ ~ color ~ _ =>
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Dig(dir, num, color)
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}
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val hexDigit = """[0-9a-f]""".r ^^ {
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case c if c.charAt(0).isDigit => c.charAt(0) - '0'
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case c => c.charAt(0) - 'a' + 10
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}
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def hexNum(len: Int) = repN(len, hexDigit).map(_.foldLeft(0)(_ * 16 + _))
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val toDir = Array(Right, Down, Left, Up)
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val digHex = hexNum(5) ~ hexDigit ^^ { case num ~ dig => Dig(toDir(dig), num, "") }
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def apply(s: String) = parse(dig, s).get
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def instructions() = lines.map(Parser(_)).toSeq
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def points(ins: Seq[Dig]) =
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ins
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.scanLeft((0L, 0L)) { case ((x, y), in) => in(x, y) }
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.dropRight(1)
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extension [T](ss: Seq[T]) def shiftLeft = ss.drop(1) ++ ss.take(1)
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def area(pts: Seq[(Long, Long)]) = pts
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.lazyZip(pts.shiftLeft)
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.map { case ((ax, ay), (bx, by)) =>
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(bx - ax) * (by + ay)
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}
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.sum
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.abs
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def circum(pts: Seq[(Long, Long)]) = pts
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.lazyZip(pts.shiftLeft)
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.map { case ((ax, ay), (bx, by)) =>
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(bx - ax).abs + (by - ay).abs
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}
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.sum
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def areaBlock(pts: Seq[(Long, Long)]) = (area(pts) + circum(pts)) / 2 + 1
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def part1 =
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val ins = instructions()
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val pts = points(ins)
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println(areaBlock(pts))
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def part2 =
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val ins = instructions().map(_.part2)
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val pts = points(ins)
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println(areaBlock(pts))
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@main def Day18(part: Int) = part match
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case 1 => part1
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case 2 => part2
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