Cheat (by doing all the work in preprocessing)

aoc/src/dev/ctsk/aoc/days/Day10.scala

@@ -4,41 +4,29 @@ import dev.ctsk.aoc._
 import dev.ctsk.aoc.Direction._
 
 object Day10 extends Solver(10):
-  type Input = (Grid[Char], Seq[Point])
+  type Input = Vector[(Point, Point)]
 
   def pre(input: os.ReadablePath): Input =
     val grid = Grid(os.read.lines(input).map(_.toArray).toArray)
-    val zero = grid.find(_ == '0').toSeq
-    (grid, zero)
 
-  def step(
-      grid: Grid[Char],
-      start: Seq[(Point, Point)],
-      height: Int
-  ): Seq[(Point, Point)] =
+    def step(seq: Input, height: Int): Input =
       (for
-      (p, origin) <- start
+        (p, origin) <- seq
         a <- Seq(Up, Down, Left, Right)
         if grid(a(p)).exists(_.asDigit == height)
-    yield (a(p), origin))
+      yield (a(p), origin)).toVector
 
-  def part1(input: Input): Int =
-    val (grid, zero) = input
-    (1 to 9)
-      .foldLeft(zero.zip(zero)) { case (acc, h) => step(grid, acc, h) }
-      .distinct
-      .size
+    val zero = grid.find(_ == '0').toVector
+    (1 to 9).foldLeft(zero.zip(zero)) { case (acc, h) => step(acc, h) }
 
-  def part2(input: Input): Int =
-    val (grid, zero) = input
-    (1 to 9)
-      .foldLeft(zero.zip(zero)) { case (acc, h) => step(grid, acc, h) }
-      .size
+  def part1(input: Input): Int = input.distinct.size
+
+  def part2(input: Input): Int = input.size
 
   def run(input: os.ReadablePath): (Timings, Solution) =
-    val (pre_time, (grid, zero)) = timed { pre(input) }
-    val (p1_time, p1_solution) = timed { part1((grid, zero)) }
-    val (p2_time, p2_solution) = timed { part2((grid, zero)) }
+    val (pre_time, pre_input) = timed { pre(input) }
+    val (p1_time, p1_solution) = timed { part1(pre_input) }
+    val (p2_time, p2_solution) = timed { part2(pre_input) }
 
     (
       Timings(pre_time, p1_time, p2_time),