day 15 puzzle 2

progress.yaml

@@ -25,4 +25,6 @@
 13:
   stars: 2
 14:
+  stars: 2
+15:
   stars: 2

res/examples/day15_1.txt

@@ -0,0 +1,10 @@
+########
+#..O.O.#
+##@.O..#
+#...O..#
+#.#.O..#
+#...O..#
+#......#
+########
+
+<^^>>>vv<v>>v<<

res/examples/day15_2.txt

@@ -0,0 +1,21 @@
+##########
+#..O..O.O#
+#......O.#
+#.OO..O.O#
+#..O@..O.#
+#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^<<^

src/day15/puzzle1.typ

@@ -0,0 +1,91 @@
+#import "/src/utils.typ": *
+
+#let WALL = "#"
+#let BOX = "O"
+#let BOT = "@"
+#let EMPTY = "."
+
+#let offsets = (
+  "^": (0, -1),
+  "<": (-1, 0),
+  "v": (0, 1),
+  ">": (1, 0)
+)
+
+#let compute-value(grid) = {
+  let total = 0
+  for (y, row) in grid.enumerate() {
+    for (x, type) in row.enumerate() {
+      if type == BOX {
+        total += y * 100 + x
+      }
+    }
+  }
+  return total
+}
+
+#let solve(input) = {
+  let (grid-data, move-data) = input.split("\n\n")
+  let grid = grid-data.split("\n").map(r => r.clusters())
+  let rows = ()
+  let cols = ()
+  
+  let w = grid.first().len()
+  let h = grid.len()
+  let bot-pos = none
+
+  for y in range(h) {
+    for x in range(w) {
+      let type = grid.at(y).at(x)
+      if type == BOT {
+        bot-pos = (x, y)
+        grid.at(y).at(x) = EMPTY
+        break
+      }
+    }
+    if bot-pos != none {
+      break
+    }
+  }
+  let (bot-x, bot-y) = bot-pos
+
+  let moves = move-data.replace("\n", "").clusters()
+  for (move-i, move) in moves.enumerate() {
+    let (dx, dy) = offsets.at(move)
+    let (x2, y2) = (bot-x + dx, bot-y + dy)
+    let type = grid.at(y2).at(x2)
+    if type == WALL {
+      continue
+    }
+    if type == EMPTY {
+      (bot-x, bot-y) = (x2, y2)
+      continue
+    }
+
+    let type2 = type
+    let (x3, y3) = (x2, y2)
+    while type2 == BOX {
+      x3 += dx
+      y3 += dy
+      type2 = grid.at(y3).at(x3)
+    }
+
+    if type2 == WALL {
+      continue
+    }
+    grid.at(y3).at(x3) = BOX
+    grid.at(y2).at(x2) = EMPTY
+    (bot-x, bot-y) = (x2, y2)
+  }
+
+  return compute-value(grid)
+}
+
+#show-puzzle(
+  15, 1,
+  solve,
+  example: (
+    "1": 2028,
+    "2": 10092
+  )
+)

src/day15/puzzle2.typ

@@ -0,0 +1,123 @@
+#import "/src/utils.typ": *
+
+#let WALL = "#"
+#let BOX = "O"
+#let BOX-L = "["
+#let BOX-R = "]"
+#let BOT = "@"
+#let EMPTY = "."
+
+#let offsets = (
+  "^": (0, -1),
+  "<": (-1, 0),
+  "v": (0, 1),
+  ">": (1, 0)
+)
+
+#let compute-value(grid) = {
+  let total = 0
+  for (y, row) in grid.enumerate() {
+    for (x, type) in row.enumerate() {
+      if type == BOX-L {
+        total += y * 100 + x
+      }
+    }
+  }
+  return total
+}
+
+#let can-move(grid, w, h, x, y, dx, dy) = {
+  let (x2, y2) = (x + dx, y + dy)
+  let type = grid.at(y2).at(x2)
+  if type == EMPTY {
+    return true
+  }
+  if type == WALL {
+    return false
+  }
+
+  // Horizontal move
+  if dy == 0 {
+    return can-move(grid, w, h, x2, y2, dx, dy)
+  }
+  
+  let lx = if type == BOX-L {x2} else {x2 - 1}
+
+  return (
+    can-move(grid, w, h, lx, y2, dx, dy) and
+    can-move(grid, w, h, lx + 1, y2, dx, dy)
+  )
+}
+
+#let do-move(grid, w, h, x, y, dx, dy) = {
+  let type = grid.at(y).at(x)
+  let (x2, y2) = (x + dx, y + dy)
+  let type2 = grid.at(y2).at(x2)
+  
+  if type2 in (BOX-L, BOX-R) {
+    grid = do-move(grid, w, h, x2, y2, dx, dy)
+    // Vertical move
+    if dx == 0 {
+      let x3 = if type2 == BOX-L {x2 + 1} else {x2 - 1}
+      grid = do-move(grid, w, h, x3, y2, dx, dy)
+    }
+    type2 = EMPTY
+  }
+  if type2 == EMPTY {
+    grid.at(y2).at(x2) = type
+    grid.at(y).at(x) = EMPTY
+    return grid
+  }
+  if type2 == WALL {
+    panic()
+  }
+  return grid
+}
+
+#let solve(input) = {
+  let (grid-data, move-data) = input.split("\n\n")
+  let grid = grid-data.split("\n").map(r => r.clusters())
+  
+  let w = grid.first().len()
+  let h = grid.len()
+  let (w2, h2) = (w * 2, h)
+  let bot-pos = none
+  let grid2 = ((EMPTY,) * w2,) * h2
+
+  for y in range(h) {
+    for x in range(w) {
+      let type = grid.at(y).at(x)
+      if type == BOT {
+        bot-pos = (x*2, y)
+        type = EMPTY
+        continue
+      }
+      grid2.at(y).at(x*2) = if type == BOX {BOX-L} else {type}
+      grid2.at(y).at(x*2 + 1) = if type == BOX {BOX-R} else {type}
+    }
+  }
+  let (bot-x, bot-y) = bot-pos
+
+  let moves = move-data.replace("\n", "").clusters()
+  for (move-i, move) in moves.enumerate() {
+    let (dx, dy) = offsets.at(move)
+    let (x2, y2) = (bot-x + dx, bot-y + dy)
+
+    if not can-move(grid2, w2, h2, bot-x, bot-y, dx, dy) {
+      continue
+    }
+
+    grid2 = do-move(grid2, w2, h2, bot-x, bot-y, dx, dy)
+    (bot-x, bot-y) = (x2, y2)
+  }
+
+  return compute-value(grid2)
+}
+
+#show-puzzle(
+  15, 2,
+  solve,
+  example: (
+    "2": 9021
+  )
+)