day 18 puzzle 2

progress.yaml

@@ -28,3 +28,9 @@
   stars: 2
 15:
   stars: 2
+16:
+  stars: 0
+17:
+  stars: 1
+18:
+  stars: 2

res/examples/day16_1.txt

@@ -0,0 +1,15 @@
+###############
+#.......#....E#
+#.#.###.#.###.#
+#.....#.#...#.#
+#.###.#####.#.#
+#.#.#.......#.#
+#.#.#####.###.#
+#...........#.#
+###.#.#####.#.#
+#...#.....#.#.#
+#.#.#.###.#.#.#
+#.....#...#.#.#
+#.###.#.#.#.#.#
+#S..#.....#...#
+###############

res/examples/day16_2.txt

@@ -0,0 +1,17 @@
+#################
+#...#...#...#..E#
+#.#.#.#.#.#.#.#.#
+#.#.#.#...#...#.#
+#.#.#.#.###.#.#.#
+#...#.#.#.....#.#
+#.#.#.#.#.#####.#
+#.#...#.#.#.....#
+#.#.#####.#.###.#
+#.#.#.......#...#
+#.#.###.#####.###
+#.#.#...#.....#.#
+#.#.#.#####.###.#
+#.#.#.........#.#
+#.#.#.#########.#
+#S#.............#
+#################

res/examples/day17_1.txt

@@ -0,0 +1,5 @@
+Register A: 729
+Register B: 0
+Register C: 0
+
+Program: 0,1,5,4,3,0

res/examples/day17_2.txt

@@ -0,0 +1,5 @@
+Register A: 2024
+Register B: 0
+Register C: 0
+
+Program: 0,3,5,4,3,0

res/examples/day18.txt

@@ -0,0 +1,25 @@
+5,4
+4,2
+4,5
+3,0
+2,1
+6,3
+2,4
+1,5
+0,6
+3,3
+2,6
+5,1
+1,2
+5,5
+2,5
+6,5
+1,4
+0,4
+6,4
+1,1
+6,1
+1,0
+0,5
+1,6
+2,0

src/day16/puzzle1.typ

@@ -0,0 +1,67 @@
+#import "/src/utils.typ": *
+
+#let START = "S"
+#let END = "E"
+#let WALL = "#"
+#let EMPTY = "."
+
+#let offsets = (
+  (1, 0),
+  (0, 1),
+  (-1, 0),
+  (0, -1)
+)
+
+#let solve(input) = {
+  let grid = input.split("\n").map(l => l.clusters())
+  let w = grid.first().len()
+  let h = grid.len()
+
+  let (sx, sy) = (0, 0)
+  let (ex, ey) = (0, 0)
+  for y in range(h) {
+    for x in range(w) {
+      let c = grid.at(y).at(x)
+      if c == START {
+        (sx, sy) = (x, y)
+      } else if c == END {
+        (ex, ey) = (x, y)
+      }
+    }
+  }
+
+  let choices = ((sx, sy, 0, 0),)
+  let (x, y, dir, score) = (0, 0, 0, 0)
+  while choices.len() != 0 {
+    let min-score = calc.min(..choices.map(c => c.last()))
+    let i = choices.position(c => c.last() == min-score)
+    (x, y, dir, score) = choices.remove(i)
+    for (d, (dx, dy)) in offsets.enumerate() {
+      // Ignore backflips
+      if calc.abs(d - dir) == 2 {
+        continue
+      }
+      let (x2, y2) = (x + dx, y + dy)
+      let c = grid.at(y2).at(x2)
+      if c == WALL {
+        continue
+      }
+      let score2 = score + 1 + if d != dir {1000} else {0}
+      if c == END {
+        return score2
+      }
+      choices.push((x2, y2, d, score2))
+    }
+    break
+  }
+  return 0
+}
+
+#show-puzzle(
+  16, 1,
+  solve,
+  example: (
+    "1": 7036,
+    "2": 11048
+  )
+)

src/day17/puzzle1.typ

@@ -0,0 +1,87 @@
+#import "/src/utils.typ": *
+
+#let ADV = 0
+#let BXL = 1
+#let BST = 2
+#let JNZ = 3
+#let BXC = 4
+#let OUT = 5
+#let BDV = 6
+#let CDV = 7
+
+#let get-combo(regs, value) = {
+  if value >= 7 {
+    panic()
+  }
+  if value <= 3 {
+    return value
+  }
+  return regs.at(value - 4)
+}
+
+#let solve(input) = {
+  let (registers, program) = input.split("\n\n")
+
+  let regs = ()
+  for line in registers.split("\n") {
+    regs.push(
+      int(
+        line.split(": ")
+            .last()
+      )
+    )
+  }
+  program = program.split(": ")
+                   .last()
+                   .split(",")
+                   .map(int)
+
+  let out = ()
+  let pc = 0
+  while pc < program.len() {
+    let op = program.at(pc)
+    let val = program.at(pc + 1)
+    if op == ADV {
+      let num = regs.at(0)
+      let den = get-combo(regs, val)
+      let res = num.bit-rshift(den)
+      regs.at(0) = res
+    } else if op == BXL {
+      regs.at(1) = regs.at(1).bit-xor(val)
+    } else if op == BST {
+      regs.at(1) = get-combo(regs, val).bit-and(0b111)
+    } else if op == JNZ {
+      if regs.at(0) != 0 {
+        pc = val
+        continue
+      }
+    } else if op == BXC {
+      regs.at(1) = regs.at(1).bit-xor(regs.at(2))
+    } else if op == OUT {
+      out.push(get-combo(regs, val).bit-and(0b111))
+    } else if op == BDV {
+      let num = regs.at(0)
+      let den = get-combo(regs, val)
+      let res = num.bit-rshift(den)
+      regs.at(1) = res
+    } else if op == CDV {
+      let num = regs.at(0)
+      let den = get-combo(regs, val)
+      let res = num.bit-rshift(den)
+      regs.at(2) = res
+    } else {
+      panic("Unknown instruction " + str(op))
+    }
+    pc += 2
+  }
+
+  return out.map(str).join(",")
+}
+
+#show-puzzle(
+  17, 1,
+  solve,
+  example: (
+    "1": "4,6,3,5,6,3,5,2,1,0"
+  )
+)

src/day17/puzzle2.typ

@@ -0,0 +1,108 @@
+#import "/src/utils.typ": *
+
+#let ADV = 0
+#let BXL = 1
+#let BST = 2
+#let JNZ = 3
+#let BXC = 4
+#let OUT = 5
+#let BDV = 6
+#let CDV = 7
+
+#let ops = ("ADV", "BXL", "BST", "JNZ", "BXC", "OUT", "BDV", "CDV")
+
+#let get-combo(regs, value) = {
+  if value >= 7 {
+    panic()
+  }
+  if value <= 3 {
+    return value
+  }
+  return regs.at(value - 4)
+}
+
+#let describe-combo(value) = {
+  if value == 7 {
+    return "<invalid>"
+  }
+  if value <= 3 {
+    return str(value)
+  }
+  return "ABC".at(value - 4)
+}
+
+#let describe(program) = {
+  let res = ""
+  res += program.map(str).join(",")
+
+  for i in range(0, program.len(), step: 2) {
+    res += "\n"
+    let op = program.at(i)
+    let val = program.at(i + 1)
+    let combo = describe-combo(val)
+
+    res += ops.at(op) + ": "
+    if op == ADV {
+      res += "A >>= " + combo
+    } else if op == BXL {
+      res += "B ^= " + str(val)
+    } else if op == BST {
+      res += "B = " + combo + " & 0b111"
+    } else if op == JNZ {
+      res += "IF A != 0 {PC = " + str(val) + "}"
+    } else if op == BXC {
+      res += "B ^= C"
+    } else if op == OUT {
+      res += "OUT(" + combo + " & 0b111)"
+    } else if op == BDV {
+      res += "B = A >> " + combo
+    } else if op == CDV {
+      res += "C = A >> " + combo
+    }
+  }
+  return res
+}
+
+#let solve(input) = {
+  let (registers, program) = input.split("\n\n")
+
+  let regs = ()
+  for line in registers.split("\n") {
+    regs.push(
+      int(
+        line.split(": ")
+            .last()
+      )
+    )
+  }
+  program = program.split(": ")
+                   .last()
+                   .split(",")
+                   .map(int)
+
+  let out = ()
+  let pc = 0
+
+  regs.first() = 0
+
+  for n in program {
+    let b = n
+  }
+  
+  return raw(block: true, describe(program))
+}
+
+Example:
+#solve(read(get-example-path(17, suffix: "2")))
+
+Input:
+#solve(get-input(17))
+
+/*
+#show-puzzle(
+  17, 2,
+  solve,
+  example: (
+    "2": 117440
+  )
+)*/

src/day18/puzzle1.typ

@@ -0,0 +1,143 @@
+#import "/src/utils.typ": *
+
+#let offsets = (
+  (1, 0),
+  (0, 1),
+  (-1, 0),
+  (0, -1)
+)
+
+#let get-lowest(nodes, scores) = {
+  let lowest-score = none
+  let lowest-i = none
+  for (i, (x, y)) in nodes.enumerate() {
+    let score = scores.at(y).at(x)
+
+    if lowest-i == none or score < lowest-score {
+      lowest-score = score
+      lowest-i = i
+    }
+  }
+
+  if lowest-i == none {
+    panic()
+  }
+  return lowest-i
+}
+
+#let make-path(parents, end) = {
+  let path = (end,)
+  let (x, y) = end
+  let pos = parents.at(y).at(x)
+  while pos != none {
+    (x, y) = pos
+    path.insert(0, pos)
+    pos = parents.at(y).at(x)
+  }
+  return path
+}
+
+#let find-path(w, h, grid) = {
+  let end = (w - 1, h - 1)
+  let (x, y) = (0, 0)
+  let open = ((x, y),)
+  let closed = ()
+  let g-scores = ((0,) * w,) * h
+  let f-scores = ((calc.inf,) * w,) * h
+  let parents = ((none,)*w,)*h
+  while open.len() != 0 {
+    let cur = open.remove(get-lowest(open, f-scores))
+    
+    if cur == end {
+      return make-path(parents, cur)
+    }
+
+    let g-score = g-scores.at(y).at(x)
+    let f-score = f-scores.at(y).at(x)
+    
+    let (x, y) = cur
+    for (dx, dy) in offsets {
+      let (x2, y2) = (x + dx, y + dy)
+      if x2 < 0 or x2 >= w or y2 < 0 or y2 >= h {
+        continue
+      }
+      if grid.at(y2).at(x2) {
+        continue
+      }
+      if (x2, y2) in closed {
+        continue
+      }
+      let g = x2 + y2
+      let h = calc.abs(end.first() - x2) + calc.abs(end.last() - y2)
+      let f = g + h
+
+      if f < f-scores.at(y2).at(x2) {
+        g-scores.at(y2).at(x2) = g
+        f-scores.at(y2).at(x2) = f
+        parents.at(y2).at(x2) = (x, y)
+        open.push((x2, y2))
+      }
+    }
+    closed.push(cur)
+  }
+  panic("No path was found")
+}
+
+#let solve(input, w: 0, h: 0, n-bytes: 0) = {
+  assert(w != 0, message: "Width cannot be 0")
+  assert(h != 0, message: "Height cannot be 0")
+  let grid = ((false,) * w,) * h
+
+  let obstacles = input.split("\n")
+  for obs in obstacles.slice(0, n-bytes) {
+    let (x, y) = obs.split(",").map(int)
+    grid.at(y).at(x) = true
+  }
+
+  let path = find-path(w, h, grid)
+  return path.len() - 1
+}
+
+#let visualize(input, w: 0, h: 0, n-bytes: 0, s: 2em) = {
+  let grid_ = ((false,) * w,) * h
+
+  let obstacles = input.split("\n")
+  for obs in obstacles.slice(0, n-bytes) {
+    let (x, y) = obs.split(",").map(int)
+    grid_.at(y).at(x) = true
+  }
+
+  let path = find-path(w, h, grid_)
+  for (x, y) in path {
+    grid_.at(y).at(x) = grid.cell(fill: green.lighten(60%))[O]
+  }
+  
+  let cells = grid_.flatten().map(c => {
+    if c == false []
+    else if c == true {grid.cell(fill: red.lighten(60%))[\#]}
+    else {c}
+  })
+  
+  grid(
+    columns: (s,) * w,
+    rows: (s,) * h,
+    align: center + horizon,
+    stroke: black,
+    ..cells
+  )
+}
+
+#show-puzzle(
+  18, 1,
+  solve.with(w: 71, h: 71, n-bytes: 1024),
+  example: (
+    (result: 22, args: (w: 7, h: 7, n-bytes: 12)),
+  ),
+  visualize: visualize.with(w: 7, h: 7, n-bytes: 12)
+)
+
+/*
+#pagebreak()
+#set page(width: auto, height: auto)
+#visualize(get-input(18), w: 71, h: 71, n-bytes: 1024, s: 1em)
+*/

src/day18/puzzle2.typ

@@ -0,0 +1,117 @@
+#import "/src/utils.typ": *
+#let offsets = (
+  (1, 0),
+  (0, 1),
+  (-1, 0),
+  (0, -1)
+)
+
+#let get-lowest(nodes, scores) = {
+  let lowest-score = none
+  let lowest-i = none
+  for (i, (x, y)) in nodes.enumerate() {
+    let score = scores.at(y).at(x)
+
+    if lowest-i == none or score < lowest-score {
+      lowest-score = score
+      lowest-i = i
+    }
+  }
+
+  if lowest-i == none {
+    panic()
+  }
+  return lowest-i
+}
+
+#let make-path(parents, end) = {
+  let path = (end,)
+  let (x, y) = end
+  let pos = parents.at(y).at(x)
+  while pos != none {
+    (x, y) = pos
+    path.insert(0, pos)
+    pos = parents.at(y).at(x)
+  }
+  return path
+}
+
+#let find-path(w, h, grid, start: (0, 0), end: auto) = {
+  let end = if end == auto {(w - 1, h - 1)} else {end}
+  let (x, y) = start
+  let open = ((x, y),)
+  let closed = ()
+  let g-scores = ((0,) * w,) * h
+  let f-scores = ((calc.inf,) * w,) * h
+  let parents = ((none,)*w,)*h
+  while open.len() != 0 {
+    let cur = open.remove(get-lowest(open, f-scores))
+    
+    if cur == end {
+      return true
+    }
+
+    let g-score = g-scores.at(y).at(x)
+    let f-score = f-scores.at(y).at(x)
+    
+    let (x, y) = cur
+    for (dx, dy) in offsets {
+      let (x2, y2) = (x + dx, y + dy)
+      if x2 < 0 or x2 >= w or y2 < 0 or y2 >= h {
+        continue
+      }
+      if grid.at(y2).at(x2) {
+        continue
+      }
+      if (x2, y2) in closed {
+        continue
+      }
+      let g = calc.abs(x2 - start.first()) + calc.abs(y2 - start.last())
+      let h = calc.abs(end.first() - x2) + calc.abs(end.last() - y2)
+      let f = g + h
+
+      if f < f-scores.at(y2).at(x2) {
+        g-scores.at(y2).at(x2) = g
+        f-scores.at(y2).at(x2) = f
+        parents.at(y2).at(x2) = (x, y)
+        open.push((x2, y2))
+      }
+    }
+    closed.push(cur)
+  }
+  return false
+}
+
+#let solve(input, w: 0, h: 0, n-bytes: 0) = {
+  assert(w != 0, message: "Width cannot be 0")
+  assert(h != 0, message: "Height cannot be 0")
+  let grid = ((false,) * w,) * h
+
+  let obstacles = input.split("\n")
+  let a = 0
+  let b = obstacles.len()
+
+  while b - a > 1 {
+    let m = calc.div-euclid(a + b, 2)
+    let grid2 = grid
+    for obs in obstacles.slice(0, m) {
+      let (x, y) = obs.split(",").map(int)
+      grid2.at(y).at(x) = true
+    }
+
+    if find-path(w, h, grid2) {
+      a = m
+    } else {
+      b = m
+    }
+  }
+  return obstacles.at(a)
+}
+
+#show-puzzle(
+  18, 2,
+  solve.with(w: 71, h: 71),
+  example: (
+    (result: "6,1", args: (w: 7, h: 7)),
+  )
+)