day3 gleam

day3/day3.gleam

···
+import gleam/int
+import gleam/io
+import gleam/list
+import gleam/result
+import gleam/string
+import simplifile
+
+pub fn main() {
+  let assert Ok(raw_input) = simplifile.read("src/day3/input.txt")
+
+  let input =
+    raw_input
+    |> string.trim
+    |> string.split("\n")
+
+  let part1 =
+    list.flat_map(input, fn(in) {
+      string.to_graphemes(in)
+      |> list.combination_pairs()
+      |> list.map(fn(x) {
+        { x.0 <> x.1 }
+        |> int.parse
+        |> result.unwrap(0)
+      })
+      |> list.sort(fn(a, b) { int.compare(b, a) })
+      |> list.take(1)
+    })
+    |> int.sum
+
+  io.println("Part 1: " <> int.to_string(part1))
+
+  let part2 =
+    list.map(input, fn(in) {
+      string.to_graphemes(in)
+      |> search_largest(12, "")
+      |> int.parse
+      |> result.unwrap(0)
+    })
+    |> int.sum
+
+  io.println("Part 2: " <> int.to_string(part2))
+}
+
+fn search_largest(gs: List(String), amount: Int, acc: String) -> String {
+  case amount {
+    0 -> acc
+    _ -> {
+      let assert [#(index, num), ..] =
+        list.reverse(gs)
+        |> list.split(amount - 1)
+        |> fn(x) {
+          list.reverse(x.1)
+          |> list.index_map(fn(x, i) { #(i, x) })
+        }
+        |> list.sort(fn(a, b) { string.compare(b.1, a.1) })
+
+      search_largest(list.drop(gs, index + 1), amount - 1, acc <> num)
+    }
+  }
+}