66 lines
1.4 KiB
Gleam
66 lines
1.4 KiB
Gleam
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import gleam/dict.{type Dict}
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import gleam/int
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import gleam/io
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import gleam/iterator
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import gleam/list.{filter, fold, index_map, map}
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import gleam/string
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import stdin.{stdin}
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const word_size = 4
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const directions = [#(1, 0), #(1, -1), #(1, 1), #(0, 1)]
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pub fn main() {
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stdin() |> read_input |> find_xmas |> io.debug
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}
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fn find_xmas(xmas_map: Dict(#(Int, Int), String)) -> Int {
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xmas_map
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|> dict.filter(fn(_, char) { char == "X" || char == "S" })
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|> dict.keys
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|> map(fn(coord) {
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directions
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|> list.count(fn(dir) {
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case
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xmas_map
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|> dict.take(traverse(coord, dir))
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|> dict.values
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{
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["X", "M", "A", "S"] -> True
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["S", "A", "M", "X"] -> True
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_ -> False
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}
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})
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})
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|> fold(0, int.add)
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}
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fn traverse(start: #(Int, Int), direction: #(Int, Int)) {
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let #(s_x, s_y) = start
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direction
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|> list.repeat(word_size)
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|> list.index_map(fn(dir, idx) {
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let #(x, y) = dir
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#(s_x + x * idx, s_y + y * idx)
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})
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}
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fn read_input(it: iterator.Iterator(String)) -> Dict(#(Int, Int), String) {
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it
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|> iterator.to_list
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|> map(string.trim)
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|> filter(not(string.is_empty))
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|> index_map(fn(str, col) {
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str
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|> string.to_graphemes
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|> index_map(fn(char, row) { #(#(row, col), char) })
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})
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|> list.flatten
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|> dict.from_list
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}
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fn not(a: fn(a) -> Bool) {
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fn(param: a) -> Bool { !a(param) }
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}
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