day 06: parallelized

gleam.toml

@@ -17,6 +17,7 @@ gleam_stdlib = ">= 0.34.0 and < 2.0.0"
 simplifile = ">= 2.2.0 and < 3.0.0"
 gleam_regexp = ">= 1.0.0 and < 2.0.0"
 gleam_yielder = ">= 1.1.0 and < 2.0.0"
+gleam_otp = ">= 0.14.1 and < 1.0.0"
 
 [dev-dependencies]
 gleeunit = ">= 1.0.0 and < 2.0.0"

manifest.toml

@@ -3,6 +3,8 @@
 
 packages = [
   { name = "filepath", version = "1.1.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "filepath", source = "hex", outer_checksum = "67A6D15FB39EEB69DD31F8C145BB5A421790581BD6AA14B33D64D5A55DBD6587" },
+  { name = "gleam_erlang", version = "0.33.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleam_erlang", source = "hex", outer_checksum = "A1D26B80F01901B59AABEE3475DD4C18D27D58FA5C897D922FCB9B099749C064" },
+  { name = "gleam_otp", version = "0.14.1", build_tools = ["gleam"], requirements = ["gleam_erlang", "gleam_stdlib"], otp_app = "gleam_otp", source = "hex", outer_checksum = "5A8CE8DBD01C29403390A7BD5C0A63D26F865C83173CF9708E6E827E53159C65" },
   { name = "gleam_regexp", version = "1.0.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleam_regexp", source = "hex", outer_checksum = "A3655FDD288571E90EE9C4009B719FEF59FA16AFCDF3952A76A125AF23CF1592" },
   { 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" },
@@ -11,6 +13,7 @@ packages = [
 ]
 
 [requirements]
+gleam_otp = { version = ">= 0.14.1 and < 1.0.0" }
 gleam_regexp = { version = ">= 1.0.0 and < 2.0.0" }
 gleam_stdlib = { version = ">= 0.34.0 and < 2.0.0" }
 gleam_yielder = { version = ">= 1.1.0 and < 2.0.0" }

src/guard_gallivant.gleam

@@ -1,6 +1,8 @@
 import gleam/dict.{type Dict}
+import gleam/io
 import gleam/list
 import gleam/option.{type Option}
+import gleam/otp/task.{async, try_await_all}
 import gleam/pair
 import gleam/result
 import gleam/string
@@ -39,7 +41,7 @@ type State =
 type AdvState =
   #(State, Bool)
 
-fn parse_line(line, y) {
+fn parse_column(line, y) {
   use grid, char, x <- list.index_fold(line, dict.new())
   dict.insert(grid, #(x, y), case char {
     "." -> Path
@@ -54,7 +56,7 @@ fn parse_grid(input: String) -> Grid {
   |> string.trim()
   |> string.split("\n")
   |> list.map(string.to_graphemes)
-  |> list.index_map(parse_line)
+  |> list.index_map(parse_column)
   |> list.reduce(dict.merge)
   |> result.unwrap(dict.new())
 }
@@ -124,8 +126,8 @@ fn next_coordinates(pos: Point, dir: Direction, g: Grid) -> #(Point, Direction)
 
 fn guard_exited(pos: Point, bounds: #(Int, Int)) -> Bool {
   let #(x, y) = pos
-  let #(max_x, max_y) = bounds
-  x > max_x || x < 0 || y < 0 || y > max_y
+  let #(mx, my) = bounds
+  x > mx || x < 0 || y < 0 || y > my
 }
 
 fn emulate(state: State) -> State {
@@ -170,12 +172,23 @@ fn add_obst(g: Grid, pt: Point) -> Grid {
   })
 }
 
-fn computer_obst_var_res(g: Grid) -> Int {
+fn computer_obst_one_var(g: Grid, obs_pos: Point) -> Bool {
+  add_obst(g, obs_pos)
+  |> init_adv_state
+  |> iterate
+  |> pair.second
+}
+
+fn computer_obst_all_var(g: Grid) -> Int {
   dict.keys(g)
-  |> list.map(add_obst(g, _))
-  |> list.map(init_adv_state)
-  |> list.map(iterate)
-  |> list.count(pair.second)
+  |> list.map(fn(obs_pos) { async(fn() { computer_obst_one_var(g, obs_pos) }) })
+  |> try_await_all(0)
+  |> list.count(fn(res) {
+    case res {
+      Ok(True) -> True
+      Ok(False) | Error(_) -> False
+    }
+  })
 }
 
 pub fn solve_a(input: String) -> Int {
@@ -189,5 +202,5 @@ pub fn solve_a(input: String) -> Int {
 // TODO: Optimize
 pub fn solve_b(input: String) -> Int {
   parse_grid(input)
-  |> computer_obst_var_res()
+  |> computer_obst_all_var
 }