1 files changed, 48 insertions, 0 deletions
diff --git a/aoc2017-gleam/src/aoc_2017/day_5.gleam b/aoc2017-gleam/src/aoc_2017/day_5.gleam
new file mode 100644
index 0000000..a0b9b80
--- /dev/null
+++ b/aoc2017-gleam/src/aoc_2017/day_5.gleam
@@ -0,0 +1,48 @@
+import gary.{type ErlangArray}
+import gary/array
+import gleam/int
+import gleam/list
+import gleam/result
+import gleam/string
+
+pub fn parse(input: String) -> ErlangArray(Int) {
+  input
+  |> string.split("\n")
+  |> list.map(int.parse)
+  |> result.values()
+  |> array.from_list(default: 0)
+  |> array.make_fixed()
+}
+
+pub fn pt_1(input: ErlangArray(Int)) {
+  next_step(input, 0, 0, part: 1)
+}
+
+pub fn pt_2(input: ErlangArray(Int)) {
+  next_step(input, 0, 0, part: 2)
+}
+
+fn next_step(
+  instructions: ErlangArray(Int),
+  pointer: Int,
+  step: Int,
+  part part: Int,
+) {
+  case array.get(from: instructions, at: pointer) {
+    Ok(distance) -> {
+      let delta = delta(distance, part)
+      let assert Ok(updated_instructions) =
+        array.set(instructions, at: pointer, put: distance + delta)
+      next_step(updated_instructions, pointer + distance, step + 1, part)
+    }
+    Error(_) -> step
+  }
+}
+
+fn delta(d: Int, part: Int) {
+  case part, d {
+    1, _ -> 1
+    _, n if n < 3 -> 1
+    _, _ -> -1
+  }
+}