day7 part1 gleam

day7/day7.gleam

···
+import gleam/dict
+import gleam/int
+import gleam/io
+import gleam/list
+import gleam/pair
+import gleam/set
+import gleam/string
+import simplifile
+
+pub fn main() {
+  let assert Ok(raw_input) = simplifile.read("src/day7/input.txt")
+
+  let assert [first, ..rest] =
+    string.trim(raw_input)
+    |> string.split("\n")
+
+  let input =
+    list.map(rest, fn(line) {
+      string.to_graphemes(line)
+      |> list.index_map(fn(x, i) { #(i, x) })
+      |> dict.from_list
+    })
+
+  let start =
+    string.to_graphemes(first)
+    |> list.index_fold(0, fn(acc, x, i) {
+      case x {
+        "S" -> i
+        _ -> acc
+      }
+    })
+
+  let part1 =
+    list.fold(input, #(0, set.from_list([start])), fn(acc, x) {
+      set.fold(acc.1, acc, fn(acc, y) {
+        case dict.get(x, y) {
+          Ok("^") -> #(
+            acc.0 + 1,
+            set.delete(acc.1, y)
+              |> set.insert(y + 1)
+              |> set.insert(y - 1),
+          )
+          _ -> acc
+        }
+      })
+    })
+    |> pair.first
+
+  io.println("Part 1: " <> int.to_string(part1))
+}