🧪 day 15 part 2, not working

src/main/scala/org/lemon/advent/year2024/Day15.scala

@@ -5,30 +5,71 @@ import org.lemon.advent.lib.`2d`._
 
 private object Day15:
 
+  def parseMoves(input: String): Seq[Direction] =
+    input.filterNot(_.isWhitespace).map(Direction.apply)
+
   def parse(input: String): (Map[Coord, Char], Seq[Direction]) =
     val Array(grid, moves) = input.split("\n\n")
-    (Coord.gridToMap(grid), moves.filterNot(_.isWhitespace).map(Direction.apply))
+    (Coord.gridToMap(grid), parseMoves(moves))
+
+  def parseWide(input: String): (Map[Coord, Char], Seq[Direction]) =
+    val Array(grid, moves) = input.split("\n\n")
+    val wide = grid.flatMap(_ match
+      case '#' => "##"
+      case 'O' => "[]"
+      case '.' => ".."
+      case '@' => "@."
+      case x => x.toString
+    )
+    (Coord.gridToMap(wide), parseMoves(moves))
 
   def step(grid: Map[Coord, Char], robit: Coord, dir: Direction): Map[Coord, Char] =
-    val moves = Iterator.iterate(robit)(_ + dir)
-      .takeWhile(!grid.get(_).exists(c => c == '#' || c == '.'))
-      .toSeq
-    val dest = moves.last + dir
-    if grid(dest) == '#' then grid
-    else
-      val shift = moves :+ dest
-      shift.reverse.sliding(2).foldLeft(grid) {
-        case (g, Seq(to, from)) => g.updated(to, g(from))
-      }.updated(robit, '.')
+    println(s"robit = $robit  moving = $dir")
+
+    val moves = Iterator.unfold(Set(robit)) { moving =>
+      println(s"moving = $moving")
+      if moving.isEmpty then None
+      else
+        val nexts = moving.map(_ + dir)
+        println(s"nexts = $nexts")
+        val boxes = nexts.flatMap(p =>
+          grid(p) match
+            case 'O' => Seq(p)
+            case '[' => Seq(p, p.right)
+            case ']' => Seq(p.left, p)
+            case _ => Seq()
+        ).filterNot(moving)
+        println(s"boxes = $boxes")
+        Some(moving -> boxes)
+    }.toSeq
+
+    println(s"moves = $moves")
+    val ret =
+      if moves.isEmpty then grid
+      else
+        val dest = moves.last.map(_ + dir)
+        if dest.exists(grid(_) == '#') then grid
+        else
+          val gapsFilled = moves.foldLeft(grid) { (g, moving) =>
+            moving.foldLeft(g) { (g, coord) => g.updated(coord, '.') }
+          }
+          moves.foldLeft(gapsFilled) { (g, moving) =>
+            moving.foldLeft(g) { (g, coord) => g.updated(coord + dir, grid(coord)) }
+          }
+
+    println(Area(ret).show(ret))
+    ret
+
+  def gps(grid: Map[Coord, Char], box: Char) =
+    grid.filter(_._2 == box).keysIterator.map(c => 100 * c.y + c.x).sum
 
   def part1(input: String) =
     val (grid, moves) = parse(input)
     val last = moves.foldLeft(grid)((g, d) => step(g, g.find(_._2 == '@').get._1, d))
-    last
-      .filter(_._2 == 'O')
-      .keysIterator
-      .map(c => 100 * c.y + c.x)
-      .sum
+    gps(last, 'O')
 
   def part2(input: String) =
-    0
+    val (grid, moves) = parseWide(input)
+    println(Area(grid).show(grid))
+    val last = moves.foldLeft(grid)((g, d) => step(g, g.find(_._2 == '@').get._1, d))
+    gps(last, '[')

src/test/scala/org/lemon/advent/year2024/Day15Test.scala

@@ -19,7 +19,7 @@ class Day15Test extends UnitTest:
     part1(in) shouldBe 2028
   }
 
-  test("part 1 example") {
+  test("part 1 large example") {
     val in = """|##########
                 |#..O..O.O#
                 |#......O.#
@@ -48,12 +48,45 @@ class Day15Test extends UnitTest:
     part1(read(file(2024)(15))) shouldBe 1448589
   }
 
-  test("part 2 example") {
-    val in = """|
-                |""".stripMargin
-    part2(in) shouldBe 0
+  test("part 2 small example") {
+    val in = """|#######
+                |#...#.#
+                |#.....#
+                |#..OO@#
+                |#..O..#
+                |#.....#
+                |#######
+                |
+                |<vv<<^^<<^^""".stripMargin
+    part2(in) shouldBe 618
   }
 
-  test("part 2") {
-    part2(read(file(2024)(15))) shouldBe 0
+  test("part 2 large example") {
+    val in = """|##########
+                |#..O..O.O#
+                |#......O.#
+                |#.OO..O.O#
+                |#[email protected].#
+                |#O#..O...#
+                |#O..O..O.#
+                |#.OO.O.OO#
+                |#....O...#
+                |##########
+                |
+                |<vv>^<v^>v>^vv^v>v<>v^v<v<^vv<<<^><<><>>v<vvv<>^v^>^<<<><<v<<<v^vv^v>^
+                |vvv<<^>^v^^><<>>><>^<<><^vv^^<>vvv<>><^^v>^>vv<>v<<<<v<^v>^<^^>>>^<v<v
+                |><>vv>v^v^<>><>>>><^^>vv>v<^^^>>v^v^<^^>v^^>v^<^v>v<>>v^v^<v>v^^<^^vv<
+                |<<v<^>>^^^^>>>v^<>vvv^><v<<<>^^^vv^<vvv>^>v<^^^^v<>^>vvvv><>>v^<<^^^^^
+                |^><^><>>><>^^<<^^v>>><^<v>^<vv>>v>>>^v><>^v><<<<v>>v<v<v>vvv>^<><<>^><
+                |^>><>^v<><^vvv<^^<><v<<<<<><^v<<<><<<^^<v<^^^><^>>^<v^><<<^>>^v<v^v<v^
+                |>^>>^v>vv>^<<^v<>><<><<v<<v><>v<^vv<<<>^^v^>^^>>><<^v>>v^v><^^>>^<>vv^
+                |<><^^>^^^<><vvvvv^v<v<<>^v<v>v<<^><<><<><<<^^<<<^<<>><<><^^^>^^<>^>v<>
+                |^^>vv<^v^v<vv>^<><v<^v>^^^>>>^^vvv^>vvv<>>>^<^>>>>>^<<^v>^vvv<>^<><<v>
+                |v^^>>><<^^<>>^v^<v^vv<>v^<<>^<^v^v><^<<<><<^<v><v<>vv>>v><v^<vv<>v^<<^""".stripMargin
+    part2(in) shouldBe 9021
   }
+
+// test("part 2") {
+//   part2(read(file(2024)(15))) should be > 1463651
+//   part2(read(file(2024)(15))) shouldBe 0
+// }