Day 4: part 1 WIP

Author: horothesun

src/main/scala/Day04.scala

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+import cats.data.Store
+import cats.syntax.all.*
+
+object Day04:
+
+//  val s: Store[Int, Option[Char]] = Store(f = _ => Some('a'), s = 0)
+//  val x: Option[Char] = s.peeks(identity)
+//  val y: List[Option[Char]] = s.experiment[List](n => List.range(start = n, end = n + 3))
+
+  case class Pos(row: Int, col: Int)
+
+  object Pos:
+    val zero = Pos(row = 0, col = 0)
+
+  case class Grid(rows: List[List[Char]]):
+
+    private val toVectors: Vector[Vector[Char]] = rows.map(_.toVector).toVector
+
+    def toStore: Store[Pos, Option[Char]] = Store(
+      p => toVectors.get(p.row).flatMap(_.get(p.col)),
+      s = Pos.zero
+    )
+
+    def allPositions: List[Pos] =
+      rows.zipWithIndex.flatMap((row, rowIndex) => row.zipWithIndex.map((_, colIndex) => Pos(rowIndex, colIndex)))
+
+  object Grid:
+    def parse(rows: List[String]): Option[Grid] = Grid(rows = rows.map(_.toList)).some

src/test/scala/Day04Suite.scala

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+import Day04.*
+import Day04Suite.*
+import cats.syntax.all.*
+import munit.ScalaCheckSuite
+import org.scalacheck.Gen
+import org.scalacheck.Prop.*
+
+class Day04Suite extends ScalaCheckSuite:
+
+  test("small input parsed correctly"):
+    assertEquals(
+      Grid.parse(rows = List("abc", "def")),
+      Grid(rows = List(List('a', 'b', 'c'), List('d', 'e', 'f'))).some
+    )
+
+  test("big input parsed to something"):
+    assert(Grid.parse(rows = bigInput).isDefined)
+
+  test("Grid.allPositions example"):
+    assertEquals(
+      Grid(rows = List(List('a', 'b', 'c'), List('d', 'e', 'f'))).allPositions,
+      List(
+        Pos(row = 0, col = 0),
+        Pos(row = 0, col = 1),
+        Pos(row = 0, col = 2),
+        Pos(row = 1, col = 0),
+        Pos(row = 1, col = 1),
+        Pos(row = 1, col = 2)
+      )
+    )
+
+  property("Grid |allPositions| = rows * columns"):
+    forAll(nonEmptyGridGen)(neg => assertEquals(neg.allPositions.length, neg.rows.length * neg.rows.head.length))
+
+object Day04Suite:
+
+  val bigInput: List[String] = getLinesFromFile("src/test/scala/day04_input.txt")
+
+  val nonEmptyGridGen: Gen[Grid] = Gen.zip(Gen.choose(1, 10), Gen.choose(1, 10)).flatMap { (r, c) =>
+    Gen.listOfN(r, Gen.listOfN(c, Gen.alphaUpperChar)).map(Grid.apply)
+  }