55 lines
1.3 KiB
Scala
55 lines
1.3 KiB
Scala
package aoc.day13
|
|
|
|
import aoc._
|
|
|
|
type Board = List[Seq[Char]]
|
|
|
|
val boards: Seq[Board] =
|
|
lines.toSeq
|
|
.splitBy(_ == "")
|
|
.map(_.map(_.toSeq).toList)
|
|
|
|
extension [T](ss: List[T])
|
|
def splits =
|
|
def loop(prefix: List[T], cur: List[T]): Seq[(List[T], List[T])] = cur match
|
|
case head :: next =>
|
|
(prefix, cur) +: loop(head +: prefix, next)
|
|
case Nil => Seq((prefix, cur))
|
|
loop(List.empty, ss)
|
|
|
|
def reflections(ok: (Board, Board, Int) => Boolean)(board: Board): Seq[Int] =
|
|
board.toList.splits.zipWithIndex
|
|
.filter {
|
|
case ((Nil, _) | (_, Nil), _) => false
|
|
case ((top, bottom), _) =>
|
|
val smudges = top.lazyZip(bottom).map(_.lazyZip(_).count(_ != _)).sum
|
|
ok(top, bottom, smudges)
|
|
}
|
|
.map(_._2)
|
|
|
|
inline def boardReflections(ok: (Board, Board, Int) => Boolean)(board: Board) =
|
|
val rowReflections = reflections(ok)(board)
|
|
val colReflections = reflections(ok)(board.transpose)
|
|
// println(s"$rowReflections $colReflections")
|
|
(rowReflections.sum * 100L + colReflections.sum)
|
|
|
|
// part 1
|
|
|
|
def part1 =
|
|
val res = boards
|
|
.map(boardReflections((_, _, s) => s == 0)(_))
|
|
.sum
|
|
println(res)
|
|
|
|
// part 2
|
|
|
|
def part2 =
|
|
val res = boards
|
|
.map(boardReflections((_, _, s) => s == 1)(_))
|
|
.sum
|
|
println(res)
|
|
|
|
@main def Day13(part: Int) = part match
|
|
case 1 => part1
|
|
case 2 => part2
|