day 14 lol

sample/day14-sample.txt

@@ -0,0 +1,12 @@
+p=0,4 v=3,-3
+p=6,3 v=-1,-3
+p=10,3 v=-1,2
+p=2,0 v=2,-1
+p=0,0 v=1,3
+p=3,0 v=-2,-2
+p=7,6 v=-1,-3
+p=3,0 v=-1,-2
+p=9,3 v=2,3
+p=7,3 v=-1,2
+p=2,4 v=2,-3
+p=9,5 v=-3,-3

src/day14_p1.gleam

@@ -0,0 +1,81 @@
+import gleam/int
+import gleam/io
+import gleam/iterator
+import gleam/list.{filter, fold, map}
+import gleam/string
+import stdin.{stdin}
+
+const w = 101
+
+const h = 103
+
+pub fn main() {
+  stdin()
+  |> read_input
+  |> map(fn(r) { move(r, 100) })
+  |> count_safety
+  |> io.debug
+}
+
+fn count_safety(robots: List(#(Int, Int))) -> Int {
+  let assert Ok(mid_col) = int.floor_divide(w, 2)
+  let assert Ok(mid_row) = int.floor_divide(h, 2)
+
+  let #(tl, tr, bl, br) =
+    robots
+    |> fold(#(0, 0, 0, 0), fn(acc, r) {
+      let #(tl, tr, bl, br) = acc
+      let #(x, y) = r
+      case x, y {
+        x, y if x < mid_col && y < mid_row -> #(tl + 1, tr, bl, br)
+        x, y if x > mid_col && y < mid_row -> #(tl, tr + 1, bl, br)
+        x, y if x < mid_col && y > mid_row -> #(tl, tr, bl + 1, br)
+        x, y if x > mid_col && y > mid_row -> #(tl, tr, bl, br + 1)
+        _, _ -> acc
+      }
+    })
+
+  tl * tr * bl * br
+}
+
+fn move(robot: Robot, times: Int) -> #(Int, Int) {
+  let Robot(#(x, y), #(xs, ys)) = robot
+  let assert Ok(nx) = int.modulo(x + xs * times, w)
+  let assert Ok(ny) = int.modulo(y + ys * times, h)
+  #(nx, ny)
+}
+
+type Robot {
+  Robot(pos: #(Int, Int), speed: #(Int, Int))
+}
+
+fn read_input(it: iterator.Iterator(String)) -> List(Robot) {
+  it
+  |> iterator.to_list
+  |> map(string.trim)
+  |> filter(not(string.is_empty))
+  |> map(parse_line)
+}
+
+fn parse_line(line: String) -> Robot {
+  let assert [coord, velocity] =
+    line
+    |> string.drop_start(2)
+    |> string.split(" v=")
+    |> map(parse_pair)
+
+  Robot(coord, velocity)
+}
+
+fn parse_pair(text: String) -> #(Int, Int) {
+  let assert [Ok(x), Ok(y)] =
+    text
+    |> string.split(",")
+    |> map(int.parse)
+
+  #(x, y)
+}
+
+fn not(a: fn(a) -> Bool) {
+  fn(param: a) -> Bool { !a(param) }
+}

src/day14_p2.gleam

@@ -0,0 +1,79 @@
+import gleam/int
+import gleam/io
+import gleam/iterator
+import gleam/list.{filter, fold, map}
+import gleam/result
+import gleam/string
+import stdin.{stdin}
+
+const w = 101
+
+const h = 103
+
+pub fn main() {
+  stdin()
+  |> read_input
+  |> find_easter_egg(0)
+  |> io.debug
+}
+
+fn find_easter_egg(robots: List(Robot), index: Int) -> Int {
+  let coords = robots |> map(fn(r) { move(r, index) })
+  case check_easter_egg(coords) {
+    True -> index
+    False -> find_easter_egg(robots, index + 1)
+  }
+}
+
+fn check_easter_egg(coords: List(#(Int, Int))) -> Bool {
+  // Lil hack, just check for a long vertical line
+  coords
+  |> list.find(fn(c) {
+    let #(x, y) = c
+    list.range(0, 10)
+    |> list.all(fn(ny) { coords |> list.contains(#(x, y + ny)) })
+  })
+  |> result.is_ok
+}
+
+fn move(robot: Robot, times: Int) -> #(Int, Int) {
+  let Robot(#(x, y), #(xs, ys)) = robot
+  let assert Ok(nx) = int.modulo(x + xs * times, w)
+  let assert Ok(ny) = int.modulo(y + ys * times, h)
+  #(nx, ny)
+}
+
+type Robot {
+  Robot(pos: #(Int, Int), speed: #(Int, Int))
+}
+
+fn read_input(it: iterator.Iterator(String)) -> List(Robot) {
+  it
+  |> iterator.to_list
+  |> map(string.trim)
+  |> filter(not(string.is_empty))
+  |> map(parse_line)
+}
+
+fn parse_line(line: String) -> Robot {
+  let assert [coord, velocity] =
+    line
+    |> string.drop_start(2)
+    |> string.split(" v=")
+    |> map(parse_pair)
+
+  Robot(coord, velocity)
+}
+
+fn parse_pair(text: String) -> #(Int, Int) {
+  let assert [Ok(x), Ok(y)] =
+    text
+    |> string.split(",")
+    |> map(int.parse)
+
+  #(x, y)
+}
+
+fn not(a: fn(a) -> Bool) {
+  fn(param: a) -> Bool { !a(param) }
+}