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