3 files changed, 129 insertions, 0 deletions
diff --git a/aoc2023/src/day12/.gitignore b/aoc2023/src/day12/.gitignore
new file mode 100644
index 0000000..ae40cea
--- /dev/null
+++ b/aoc2023/src/day12/.gitignore
@@ -0,0 +1 @@
+input.txt
+\ No newline at end of file
diff --git a/aoc2023/src/day12/solve.gleam b/aoc2023/src/day12/solve.gleam
new file mode 100644
index 0000000..578fa5f
--- /dev/null
+++ b/aoc2023/src/day12/solve.gleam
@@ -0,0 +1,80 @@
+import adglent.{First, Second}
+import gleam/io
+import gleam/string
+import gleam/list
+import gleam/int
+import gleam/result
+import gleam/dict.{type Dict}
+
+fn parse_folds(input: String, folds: Int) {
+  let records = string.split(input, "\n")
+  use record <- list.map(records)
+  let assert Ok(#(template, sets_str)) = string.split_once(record, " ")
+
+  let template =
+    template
+    |> list.repeat(folds)
+    |> list.intersperse("?")
+    |> string.concat
+  let sets =
+    sets_str
+    |> string.split(",")
+    |> list.map(int.parse)
+    |> result.values
+    |> list.repeat(folds)
+    |> list.flatten()
+
+  #(template, sets)
+}
+
+fn do_count(template: String, groups: List(Int), left: Int, gap: Bool) -> Int {
+  case template, groups, left, gap {
+    "", [], 0, _ -> 1
+    "?" <> t_rest, [g, ..g_rest], 0, False ->
+      do_count(t_rest, g_rest, g - 1, g == 1) + {
+        do_count(t_rest, groups, 0, False)
+      }
+    "?" <> t_rest, [], 0, False
+    | "?" <> t_rest, _, 0, True
+    | "." <> t_rest, _, 0, _ -> do_count(t_rest, groups, 0, False)
+    "#" <> t_rest, [g, ..g_rest], 0, False ->
+      do_count(t_rest, g_rest, g - 1, g == 1)
+    "?" <> t_rest, gs, l, False | "#" <> t_rest, gs, l, False ->
+      do_count(t_rest, gs, l - 1, l == 1)
+    _, _, _, _ -> 0
+  }
+}
+
+fn count_solutions(acc: Int, condition: #(String, List(Int))) -> Int {
+  let #(template, groups) = condition
+  acc + do_count(template, groups, 0, False)
+}
+
+pub fn part1(input: String) {
+  input
+  |> parse_folds(1)
+  |> list.fold(0, count_solutions)
+  |> string.inspect
+}
+
+pub fn part2(input: String) {
+  input
+  |> parse_folds(5)
+  |> list.fold(0, count_solutions)
+  |> string.inspect
+}
+
+pub fn main() {
+  let assert Ok(part) = adglent.get_part()
+  let assert Ok(input) = adglent.get_input("12")
+  case part {
+    First ->
+      part1(input)
+      |> adglent.inspect
+      |> io.println
+    Second ->
+      part2(input)
+      |> adglent.inspect
+      |> io.println
+  }
+}
diff --git a/aoc2023/test/day12/day12_test.gleam b/aoc2023/test/day12/day12_test.gleam
new file mode 100644
index 0000000..3daf0e9
--- /dev/null
+++ b/aoc2023/test/day12/day12_test.gleam
@@ -0,0 +1,48 @@
+import gleam/list
+import showtime/tests/should
+import adglent.{type Example, Example}
+import day12/solve
+
+type Problem1AnswerType =
+  String
+
+type Problem2AnswerType =
+  String
+
+/// Add examples for part 1 here:
+/// ```gleam
+///const part1_examples: List(Example(Problem1AnswerType)) = [Example("some input", "")]
+/// ```
+const part1_examples: List(Example(Problem1AnswerType)) = [
+  Example(
+    "???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1",
+    "21",
+  ),
+]
+
+/// Add examples for part 2 here:
+/// ```gleam
+///const part2_examples: List(Example(Problem2AnswerType)) = [Example("some input", "")]
+/// ```
+const part2_examples: List(Example(Problem2AnswerType)) = []
+
+pub fn part1_test() {
+  part1_examples
+  |> should.not_equal([])
+  use example <- list.map(part1_examples)
+  solve.part1(example.input)
+  |> should.equal(example.answer)
+}
+
+pub fn part2_test() {
+  part2_examples
+  |> should.not_equal([])
+  use example <- list.map(part2_examples)
+  solve.part2(example.input)
+  |> should.equal(example.answer)
+}