1 files changed, 87 insertions, 0 deletions
diff --git a/aoc2017-gleam/src/aoc_2017/day_3.gleam b/aoc2017-gleam/src/aoc_2017/day_3.gleam
new file mode 100644
index 0000000..5672e39
--- /dev/null
+++ b/aoc2017-gleam/src/aoc_2017/day_3.gleam
@@ -0,0 +1,87 @@
+import gleam/dict
+import gleam/int
+import gleam/list
+
+type Direction {
+  Up
+  Down
+  Left
+  Right
+}
+
+type State {
+  State(
+    x: Int,
+    y: Int,
+    direction: Direction,
+    branch_length: Int,
+    remaining: Int,
+  )
+}
+
+fn starting_state() -> State {
+  State(0, 0, Right, 1, 1)
+}
+
+fn update_state(state: State) -> State {
+  case state {
+    State(x, y, Right, len, 0) -> State(x, y + 1, Up, len, len - 1)
+    State(x, y, Up, len, 0) -> State(x - 1, y, Left, len + 1, len)
+    State(x, y, Left, len, 0) -> State(x, y - 1, Down, len, len - 1)
+    State(x, y, Down, len, 0) -> State(x + 1, y, Right, len + 1, len)
+    State(x, y, Right, len, rem) -> State(x + 1, y, Right, len, rem - 1)
+    State(x, y, Up, len, rem) -> State(x, y + 1, Up, len, rem - 1)
+    State(x, y, Left, len, rem) -> State(x - 1, y, Left, len, rem - 1)
+    State(x, y, Down, len, rem) -> State(x, y - 1, Down, len, rem - 1)
+  }
+}
+
+type Grid =
+  dict.Dict(#(Int, Int), Int)
+
+pub fn parse(input: String) -> Int {
+  let assert Ok(n) = int.parse(input)
+  n
+}
+
+pub fn pt_1(input: Int) -> Int {
+  next_step(1, input, starting_state())
+}
+
+fn next_step(current: Int, target: Int, state: State) -> Int {
+  case current == target {
+    True -> int.absolute_value(state.x) + int.absolute_value(state.y)
+    False -> next_step(current + 1, target, update_state(state))
+  }
+}
+
+pub fn pt_2(input: Int) -> Int {
+  let grid: Grid = dict.from_list([#(#(0, 0), 1)])
+
+  add_next_cell(input, starting_state(), grid)
+}
+
+fn neighbors(coord: #(Int, Int)) -> List(#(Int, Int)) {
+  let #(x, y) = coord
+
+  use dx <- list.flat_map(list.range(-1, 1))
+  use dy <- list.map(list.range(-1, 1))
+  #(x + dx, y + dy)
+}
+
+fn add_next_cell(target: Int, state: State, grid: Grid) -> Int {
+  let next_cell = update_state(state)
+  let coords = #(next_cell.x, next_cell.y)
+  let value =
+    list.fold(neighbors(coords), 0, fn(acc, coord) {
+      case dict.get(grid, coord) {
+        Ok(n) -> acc + n
+        _err -> acc
+      }
+    })
+
+  case value >= target {
+    True -> value
+    False -> add_next_cell(target, next_cell, dict.insert(grid, coords, value))
+  }
+}