Finish day 11

1 files changed, 26 insertions, 0 deletions

diff --git a/aoc-2020-gleam/src/util/pos.gleam b/aoc-2020-gleam/src/util/pos.gleam
new file mode 100644
index 0000000..a060440
--- /dev/null
+++ b/aoc-2020-gleam/src/util/pos.gleam
@@ -0,0 +1,26 @@
+import gleam/list
+import gleam/set.{Set}
+
+pub type Pos =
+  #(Int, Int)
+
+pub const directions8 = [
+  #(1, 0),
+  #(1, 1),
+  #(0, 1),
+  #(-1, 1),
+  #(-1, 0),
+  #(-1, -1),
+  #(0, -1),
+  #(1, -1),
+]
+
+pub fn add(p1: Pos, p2: Pos) -> Pos {
+  #(p1.0 + p2.0, p1.1 + p2.1)
+}
+
+pub fn neighbours8(pos: Pos) -> Set(Pos) {
+  directions8
+  |> list.map(with: add(pos, _))
+  |> set.from_list
+}