Solve part 1 of day 24

3 files changed, 84 insertions, 4 deletions

diff --git a/aoc-2020-gleam/src/days/day24.gleam b/aoc-2020-gleam/src/days/day24.gleam
new file mode 100644
index 0000000..66bedb8
--- /dev/null
+++ b/aoc-2020-gleam/src/days/day24.gleam
@@ -0,0 +1,51 @@
+import gleam/io
+import gleam/set
+import gleam/list
+import ext/setx
+import ext/resultx as resx
+import util/input_util
+import util/parser as p
+import util/hex.{type Hex}
+
+fn parse_tiles(lines: List(String)) -> List(Hex) {
+  let tile_parser =
+    [
+      p.replace(p.literal("e"), with: hex.e),
+      p.replace(p.literal("se"), with: hex.se),
+      p.replace(p.literal("sw"), with: hex.sw),
+      p.replace(p.literal("w"), with: hex.w),
+      p.replace(p.literal("nw"), with: hex.nw),
+      p.replace(p.literal("ne"), with: hex.ne),
+    ]
+    |> p.any
+    |> p.many1
+    |> p.map(with: list.fold(over: _, from: hex.zero, with: hex.add))
+
+  list.map(lines, with: fn(line) {
+    line
+    |> p.parse_entire(with: tile_parser)
+    |> resx.assert_unwrap
+  })
+}
+
+fn part1(lines: List(String)) -> Int {
+  let tiles = parse_tiles(lines)
+  let blacks = list.fold(over: tiles, from: set.new(), with: setx.toggle)
+  set.size(blacks)
+}
+
+fn part2(lines: List(String)) -> Nil {
+  Nil
+}
+
+pub fn main() -> Nil {
+  let testing = input_util.read_lines("test24")
+  let assert 10 = part1(testing)
+  io.debug(part2(testing))
+
+  let input = input_util.read_lines("day24")
+  io.debug(part1(input))
+  io.debug(part2(input))
+
+  Nil
+}
diff --git a/aoc-2020-gleam/src/ext/setx.gleam b/aoc-2020-gleam/src/ext/setx.gleam
index 68d185a..6df9256 100644
--- a/aoc-2020-gleam/src/ext/setx.gleam
+++ b/aoc-2020-gleam/src/ext/setx.gleam
@@ -3,16 +3,24 @@ import gleam/set.{type Set}
 import gleam/iterator as iter
 import ext/iteratorx as iterx
 
-pub fn count(set: Set(a), satisfying predicate: fn(a) -> Bool) -> Int {
-  set
+pub fn count(s: Set(a), satisfying predicate: fn(a) -> Bool) -> Int {
+  s
   |> set.to_list
   |> iter.from_list
   |> iterx.count(satisfying: predicate)
 }
 
-pub fn map(set: Set(a), with fun: fn(a) -> b) -> Set(b) {
-  set
+pub fn map(s: Set(a), with fun: fn(a) -> b) -> Set(b) {
+  s
   |> set.to_list
   |> list.map(with: fun)
   |> set.from_list
 }
+
+pub fn toggle(in s: Set(a), this value: a) -> Set(a) {
+  s
+  |> case set.contains(in: s, this: value) {
+    True -> set.delete(from: _, this: value)
+    False -> set.insert(into: _, this: value)
+  }
+}
diff --git a/aoc-2020-gleam/src/util/hex.gleam b/aoc-2020-gleam/src/util/hex.gleam
new file mode 100644
index 0000000..21db192
--- /dev/null
+++ b/aoc-2020-gleam/src/util/hex.gleam
@@ -0,0 +1,21 @@
+pub opaque type Hex {
+  Hex(q: Int, r: Int, s: Int)
+}
+
+pub const zero = Hex(q: 0, r: 0, s: 0)
+
+pub const e = Hex(q: 1, r: 0, s: -1)
+
+pub const se = Hex(q: 0, r: 1, s: -1)
+
+pub const sw = Hex(q: -1, r: 1, s: 0)
+
+pub const w = Hex(q: -1, r: 0, s: 1)
+
+pub const nw = Hex(q: 0, r: -1, s: 1)
+
+pub const ne = Hex(q: 1, r: -1, s: 0)
+
+pub fn add(a: Hex, b: Hex) -> Hex {
+  Hex(q: a.q + b.q, r: a.r + b.r, s: a.s + b.s)
+}