my aoc solutions
day 4
+92
+92
src/aoc_2025/day_4.gleam
+92
src/aoc_2025/day_4.gleam
···
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import gleam/dict
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import gleam/list
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import gleam/result
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import gleam/string
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pub fn parse(input: String) -> dict.Dict(#(Int, Int), Storage) {
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input
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|> string.split("\n")
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|> list.index_fold(dict.new(), fn(grid, row, row_index) {
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row
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|> string.to_graphemes()
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|> list.index_fold(grid, fn(grid, column, column_index) {
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let location = case column {
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"." -> Empty
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"@" -> Roll
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_ -> panic as "invalid input"
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}
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dict.insert(grid, #(row_index, column_index), location)
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})
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})
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}
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pub type Storage {
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Roll
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Empty
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}
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pub fn pt_1(warehouse: dict.Dict(#(Int, Int), Storage)) {
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warehouse
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|> dict.filter(fn(coord, storage) { can_access(warehouse, coord, storage) })
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|> dict.values()
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|> list.length()
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}
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fn can_access(warehouse, coord, storage) {
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case storage {
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Empty -> False
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Roll -> {
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let #(row, column) = coord
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let top_left =
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dict.get(warehouse, #(row - 1, column - 1)) |> result.unwrap(Empty)
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let top_middle =
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dict.get(warehouse, #(row - 1, column)) |> result.unwrap(Empty)
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let top_right =
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dict.get(warehouse, #(row - 1, column + 1)) |> result.unwrap(Empty)
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let left_middle =
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dict.get(warehouse, #(row, column - 1)) |> result.unwrap(Empty)
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let right_middle =
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dict.get(warehouse, #(row, column + 1)) |> result.unwrap(Empty)
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let bottom_left =
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dict.get(warehouse, #(row + 1, column - 1)) |> result.unwrap(Empty)
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let bottom_middle =
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dict.get(warehouse, #(row + 1, column)) |> result.unwrap(Empty)
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let bottom_right =
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dict.get(warehouse, #(row + 1, column + 1)) |> result.unwrap(Empty)
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[
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top_left,
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top_middle,
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top_right,
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left_middle,
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right_middle,
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bottom_left,
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bottom_middle,
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bottom_right,
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]
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|> list.count(fn(item) { item == Roll })
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< 4
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}
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}
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}
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pub fn pt_2(warehouse: dict.Dict(#(Int, Int), Storage)) {
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pt_2_loop(warehouse, 0)
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}
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fn pt_2_loop(warehouse, count) {
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let accessible =
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warehouse
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|> dict.filter(fn(coord, storage) { can_access(warehouse, coord, storage) })
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|> dict.keys()
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case accessible {
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[] -> count
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_ -> {
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let warehouse = warehouse |> dict.drop(accessible)
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pt_2_loop(warehouse, count + list.length(accessible))
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}
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}
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}