day 11 (p2 wip)

sample/day11-sample.txt

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+125 17

src/day11_p1.gleam

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+import gleam/int
+import gleam/io
+import gleam/iterator
+import gleam/list.{filter, filter_map, map, reverse}
+import gleam/result
+import gleam/string
+import stdin.{stdin}
+
+pub fn main() {
+  stdin()
+  |> read_input
+  |> blink_n(25)
+  |> list.length
+  |> io.debug
+}
+
+fn blink_n(stones: List(Int), remaining: Int) -> List(Int) {
+  case remaining {
+    0 -> stones
+    n -> blink_n(blink(stones), n - 1)
+  }
+}
+
+fn blink(stones: List(Int)) -> List(Int) {
+  stones |> map(blink_stone) |> list.flatten
+}
+
+fn blink_stone(stone: Int) -> List(Int) {
+  let assert Ok(digits) = int.digits(stone, 10)
+  let digit_num = digits |> list.length
+  case digits, digit_num {
+    [0], _ -> [1]
+    _, num if num % 2 == 0 -> digits |> split_half(digit_num)
+    _, _ -> [stone * 2024]
+  }
+}
+
+fn split_half(digits: List(Int), index: Int) -> List(Int) {
+  let #(first, second) = digits |> list.split(index / 2)
+  let assert Ok(out) =
+    [first, second]
+    |> map(fn(x) { int.undigits(x, 10) })
+    |> result.all
+  out
+}
+
+fn read_input(it: iterator.Iterator(String)) -> List(Int) {
+  it
+  |> iterator.fold([[]], fn(acc, line) {
+    case string.trim(line) {
+      "" -> acc
+      str -> {
+        [str |> string.split(" ") |> filter_map(int.parse), ..acc]
+      }
+    }
+  })
+  |> filter(fn(l) { list.length(l) > 0 })
+  |> reverse
+  |> list.flatten
+}

src/day11_p2.gleam

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+import gleam/dict.{type Dict}
+import gleam/int
+import gleam/io
+import gleam/iterator
+import gleam/list.{filter, filter_map, fold, map, reverse}
+import gleam/string
+import stdin.{stdin}
+
+pub fn main() {
+  stdin()
+  |> read_input
+  |> blink_n(25)
+  |> list.length
+  |> io.debug
+}
+
+fn blink_n(stones: List(Int), remaining: Int) -> List(Int) {
+  io.debug(remaining)
+  let memo = dict.new()
+}
+
+fn blink_memo(
+  memo: Dict(Int, List(Int)),
+  stone: Int,
+) -> #(Dict(Int, List(Int)), List(Int)) {
+  case dict.get(memo, stone) {
+    Ok(lst) -> #(memo, lst)
+    _ -> {
+      let res = blink_stone(stone)
+      #(dict.insert(memo, stone, res), res)
+    }
+  }
+}
+
+fn blink_stone(stone: Int) -> List(Int) {
+  let assert Ok(digits) = int.digits(stone, 10)
+  let digit_num = digits |> list.length
+  case digits, digit_num {
+    [0], _ -> [1]
+    _, num if num % 2 == 0 -> digits |> split_half(digit_num)
+    _, _ -> [stone * 2024]
+  }
+}
+
+fn split_half(digits: List(Int), index: Int) -> List(Int) {
+  let #(first, second) = digits |> list.split(index / 2)
+  let assert Ok(first) = int.undigits(first, 10)
+  let assert Ok(second) = int.undigits(second, 10)
+  [first, second]
+}
+
+fn read_input(it: iterator.Iterator(String)) -> List(Int) {
+  it
+  |> iterator.fold([[]], fn(acc, line) {
+    case string.trim(line) {
+      "" -> acc
+      str -> {
+        [str |> string.split(" ") |> filter_map(int.parse), ..acc]
+      }
+    }
+  })
+  |> filter(fn(l) { list.length(l) > 0 })
+  |> reverse
+  |> list.flatten
+}