Day08

day08/gleam.toml

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+name = "day08"
+version = "1.0.0"
+
+# Fill out these fields if you intend to generate HTML documentation or publish
+# your project to the Hex package manager.
+#
+# description = ""
+# licences = ["Apache-2.0"]
+# repository = { type = "github", user = "", repo = "" }
+# links = [{ title = "Website", href = "" }]
+#
+# For a full reference of all the available options, you can have a look at
+# https://gleam.run/writing-gleam/gleam-toml/.
+
+[dependencies]
+gleam_stdlib = ">= 0.34.0 and < 2.0.0"
+simplifile = ">= 2.2.0 and < 3.0.0"
+gleam_yielder = ">= 1.1.0 and < 2.0.0"
+gleam_community_maths = ">= 1.1.1 and < 2.0.0"
+
+[dev-dependencies]
+gleeunit = ">= 1.0.0 and < 2.0.0"

day08/input.txt

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+.I.........................................U......
+.....................9.......N........G.........U.
+....................................GN............
+...j.....A...S....................................
+.j...o...S......t.....9...........................
+..................................................
+.....3...................9.....................G..
+..I.....3...........................iG.x..2.......
+......o...j...Sh.......x...t..........U....2......
+.r...I.o.b.w.....h...............U............M..i
+3...w......7......................................
+......S.r.......h...................N.............
+........7..r..........5.h.........................
+....J.......7B......x...O..........y..............
+......I...J..a..x..............O.......H..........
+w..Fj..............t.O................H......2....
+........a..m..........y...O.4.............l.......
+.....Jm....................4......................
+..m.......................2.Ny..............M.H...
+.......a................X.....5k.....M.........H..
+.........F...........A...................M.K......
+.......7...........m....t...y.........K...........
+....i.....................B.......................
+.................5................6...............
+........b..T................ABK....i..............
+....................s..................K..........
+.....w...J.............s.................W......n.
+..............F........X...8......................
+...........4..................s...........W....f..
+.........g.....so.B.9..Y........4............6...f
+..................................................
+b......1....................8..................W..
+Lb...g.R..0...................Y................l..
+................................n...........f...l.
+..........g..............n8.....k......6..........
+.....R....A0.......................n..........W..l
+...............................d..............6...
+........................k..................D......
+...0............X......8.k........F...............
+....a....L..............Y.................D.......
+.........1...L.........u...D.......Yd.............
+.............................d...u................
+........R...................................D....X
+............L.g.0.................................
+..................................................
+..............................T...................
+........................T.........................
+....................u..........T..................
+....1...................u.........................
+..................R...................d...........

day08/manifest.toml

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+# This file was generated by Gleam
+# You typically do not need to edit this file
+
+packages = [
+  { name = "filepath", version = "1.1.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "filepath", source = "hex", outer_checksum = "67A6D15FB39EEB69DD31F8C145BB5A421790581BD6AA14B33D64D5A55DBD6587" },
+  { name = "gleam_community_maths", version = "1.1.1", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleam_community_maths", source = "hex", outer_checksum = "6C4ED7BC7E7DF6977719B5F2CFE717EE8280D1CF6EA81D55FD9953758C7FD14E" },
+  { name = "gleam_stdlib", version = "0.45.0", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "206FCE1A76974AECFC55AEBCD0217D59EDE4E408C016E2CFCCC8FF51278F186E" },
+  { name = "gleam_yielder", version = "1.1.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleam_yielder", source = "hex", outer_checksum = "8E4E4ECFA7982859F430C57F549200C7749823C106759F4A19A78AEA6687717A" },
+  { name = "gleeunit", version = "1.2.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleeunit", source = "hex", outer_checksum = "F7A7228925D3EE7D0813C922E062BFD6D7E9310F0BEE585D3A42F3307E3CFD13" },
+  { name = "simplifile", version = "2.2.0", build_tools = ["gleam"], requirements = ["filepath", "gleam_stdlib"], otp_app = "simplifile", source = "hex", outer_checksum = "0DFABEF7DC7A9E2FF4BB27B108034E60C81BEBFCB7AB816B9E7E18ED4503ACD8" },
+]
+
+[requirements]
+gleam_community_maths = { version = ">= 1.1.1 and < 2.0.0" }
+gleam_stdlib = { version = ">= 0.34.0 and < 2.0.0" }
+gleam_yielder = { version = ">= 1.1.0 and < 2.0.0" }
+gleeunit = { version = ">= 1.0.0 and < 2.0.0" }
+simplifile = { version = ">= 2.2.0 and < 3.0.0" }

day08/small-in.txt

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+............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............

day08/src/day08.gleam

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+import gleam/io
+import gleam/list
+import gleam/result
+import gleam/set
+import gleam/string
+import gleam/yielder
+import gleam_community/maths/arithmetics
+import simplifile
+
+type Coord {
+  Coord(row: Int, col: Int)
+}
+
+fn smallest_step(c: Coord) {
+  let gcd = arithmetics.gcd(c.row, c.col)
+  Coord(c.row / gcd, c.col / gcd)
+}
+
+fn add_coord(a: Coord, b: Coord) {
+  Coord(a.row + b.row, a.col + b.col)
+}
+
+fn sub_coord(a: Coord, b: Coord) {
+  Coord(a.row - b.row, a.col - b.col)
+}
+
+fn neg_coord(c: Coord) {
+  Coord(-c.row, -c.col)
+}
+
+type Map {
+  Map(rows: Int, cols: Int, map: List(List(Coord)))
+}
+
+fn parse_grid(input: String) -> Map {
+  let lines = string.split(input, "\n")
+
+  let height = list.length(lines)
+  let width =
+    string.length(list.first(lines) |> result.lazy_unwrap(fn() { panic }))
+
+  let grid =
+    lines
+    |> list.index_map(fn(row, y) {
+      string.split(row, "")
+      |> list.index_map(fn(el, x) { #(el, Coord(y, x)) })
+      |> list.filter(fn(x) { x.0 != "." })
+    })
+    |> list.flatten
+    |> list.sort(fn(a, b) { string.compare(a.0, b.0) })
+    |> list.chunk(fn(x) { x.0 })
+    |> list.map(fn(chunk) { chunk |> list.map(fn(x) { x.1 }) })
+
+  Map(height, width, grid)
+}
+
+fn calc_interference(antennas: List(Coord)) -> set.Set(Coord) {
+  antennas
+  |> list.combination_pairs
+  |> list.map(fn(p) {
+    let #(a, b) = p
+    let d = sub_coord(b, a)
+    set.from_list([sub_coord(a, d), add_coord(b, d)])
+  })
+  |> list.fold(set.new(), set.union)
+}
+
+fn in_grid(c: Coord, rows: Int, cols: Int) -> Bool {
+  c.row >= 0 && c.col >= 0 && c.row < rows && c.col < cols
+}
+
+pub fn part1(input: String) -> Int {
+  let Map(rows, cols, map) = parse_grid(input)
+
+  map
+  |> list.map(calc_interference)
+  |> list.fold(set.new(), set.union)
+  |> set.filter(in_grid(_, rows, cols))
+  |> set.size
+}
+
+fn calc_infinite_interference(
+  antennas: List(Coord),
+  rows: Int,
+  cols: Int,
+) -> set.Set(Coord) {
+  let step = fn(from: Coord, by: Coord) -> set.Set(Coord) {
+    from
+    |> yielder.iterate(add_coord(_, by))
+    |> yielder.take_while(in_grid(_, rows, cols))
+    |> yielder.fold(set.new(), set.insert)
+  }
+
+  antennas
+  |> list.combination_pairs
+  |> list.map(fn(p) {
+    let #(a, b) = p
+    let d = smallest_step(Coord(a.row - b.row, a.col - b.col))
+    set.union(step(a, d), step(b, neg_coord(d)))
+  })
+  |> list.fold(set.new(), set.union)
+}
+
+pub fn part2(input: String) -> Int {
+  let Map(rows, cols, map) = parse_grid(input)
+
+  map
+  |> list.map(calc_infinite_interference(_, rows, cols))
+  |> list.fold(set.new(), set.union)
+  |> set.size
+}
+
+pub fn main() {
+  let input =
+    simplifile.read("input.txt")
+    |> result.lazy_unwrap(fn() { panic })
+    |> string.trim
+
+  io.println("Part 1: " <> string.inspect(part1(input)))
+  io.println("Part 2: " <> string.inspect(part2(input)))
+}

day08/test/day08_test.gleam

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+import gleam/result
+import gleam/string
+import gleeunit
+import gleeunit/should
+import simplifile
+
+import day08
+
+fn input() -> String {
+  simplifile.read("small-in.txt")
+  |> result.lazy_unwrap(fn() { panic })
+  |> string.trim
+}
+
+pub fn main() {
+  gleeunit.main()
+}
+
+pub fn part1_test() {
+  day08.part1(input())
+  |> should.equal(14)
+}
+
+pub fn part2_test() {
+  day08.part2(input())
+  |> should.equal(34)
+}