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Day12 JR
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import scala.annotation.tailrec | |
object Day12HillClimbing extends App { | |
val startGrid = scala.io.Source.fromFile("./Sources/Day12HillClimbing.txt").getLines().toVector.map(_.toVector) | |
val sizeY = startGrid.length | |
val sizeX = startGrid(0).length | |
val startPosition: (Int, Int) = (0 to sizeY-1).flatMap(y => (0 to sizeX-1).map(x => if(startGrid(y)(x)== 'S') Some(y,x) else None )).filter(_.isDefined).map(_.get)(0) | |
val finishPosition: (Int, Int) = (0 to sizeY-1).flatMap(y => (0 to sizeX-1).map(x => if(startGrid(y)(x)== 'E') Some(y,x) else None )).filter(_.isDefined).map(_.get)(0) | |
def update[A](vec: Vector[Vector[A]], coord: (Int,Int), value: A): Vector[Vector[A]] = | |
vec.updated(coord._1, vec(coord._1).updated(coord._2, value)) | |
val grid: Vector[Vector[Char]] = update(update(startGrid, startPosition, 'a'), finishPosition, 'z') // remove S and E from grid | |
def nextStep(accuClimbGrid: Vector[Vector[Option[Int]]]): Vector[Vector[Option[Int]]] = { | |
(0 to sizeY - 1).map(y => (0 to sizeX - 1).map { x => | |
accuClimbGrid(y)(x) match { | |
case Some(a) => Some(a) | |
case None => { | |
val v = Vector( | |
(if (y-1 >= 0 && grid(y-1)(x).toInt + 1 >= grid(y)(x).toInt && accuClimbGrid(y-1)(x).isDefined) Some(accuClimbGrid(y-1)(x).get) else None), | |
(if (y+1 < sizeY && grid(y+1)(x).toInt + 1 >= grid(y)(x).toInt && accuClimbGrid(y+1)(x).isDefined) Some(accuClimbGrid(y+1)(x).get) else None), | |
(if (x-1 >= 0 && grid(y)(x-1).toInt + 1 >= grid(y)(x).toInt && accuClimbGrid(y)(x-1).isDefined) Some(accuClimbGrid(y)(x-1).get) else None), | |
(if (x+1 < sizeX && grid(y)(x+1).toInt + 1 >= grid(y)(x).toInt && accuClimbGrid(y)(x+1).isDefined) Some(accuClimbGrid(y)(x+1).get) else None), | |
).filter(_.isDefined) | |
if (v.isEmpty) None else Some(v.map(_.get).min + 1) // take lowest available number_of_steps + 1 from neighbours | |
} | |
} | |
}.toVector).toVector | |
} | |
@tailrec | |
def climb(accuClimbGrid: Vector[Vector[Option[Int]]]): Vector[Vector[Option[Int]]] = { | |
if (accuClimbGrid(finishPosition._1)(finishPosition._2).isDefined) accuClimbGrid | |
else climb(nextStep(accuClimbGrid)) | |
} | |
// Part 1 | |
val climbGridPart1: Vector[Vector[Option[Int]]] = startGrid.map(y => y.map(x => if(x == 'S') Some(0) else None)) | |
val climbedGridPart1: Vector[Vector[Option[Int]]] = climb(climbGridPart1) | |
val shortestPathPart1 = climbedGridPart1(finishPosition._1)(finishPosition._2).get | |
println(s"Shortest path from Start to Finish is: ${shortestPathPart1}") | |
// Part 2 | |
val climbGridPart2: Vector[Vector[Option[Int]]] = startGrid.map(y => y.map(x => if(x == 'S' || x == 'a') Some(0) else None)) | |
val climbedGridPart2 = climb(climbGridPart2) | |
val shortestPathPart2 = climbedGridPart2(finishPosition._1)(finishPosition._2).get | |
println(s"Shortest path from any lowest point to Finish is: ${shortestPathPart2}") | |
} |
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