tim.gadanidis.ca
advent of code 2025 solutions in Gleam
day07: solve part 2
+78
-17
+56
-17
src/day07.gleam
+56
-17
src/day07.gleam
···
5
5
import utils
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6
7
7
pub type Tile {
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-
Takyon
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+
Takyon(Int)
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Splitter
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ActivatedSplitter
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Empty
···
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case col {
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"^" -> #(#(x, y), Splitter)
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"." -> #(#(x, y), Empty)
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-
"S" -> #(#(x, y), Takyon)
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+
"S" -> #(#(x, y), Takyon(1))
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_ -> panic as "Invalid character"
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}
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})
···
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pub fn process_row(diagram: Diagram, row: Int) -> Diagram {
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let current_takyons =
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diagram
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-
|> dict.filter(fn(key, value) { key.1 == row && value == Takyon })
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-
|> dict.keys
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+
|> dict.filter(fn(key, value) {
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key.1 == row
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&& case value {
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Takyon(_) -> True
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_ -> False
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}
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})
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|> dict.to_list
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process_row_loop(diagram, current_takyons)
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}
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-
pub fn process_row_loop(diagram: Diagram, takyons: List(#(Int, Int))) {
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pub fn add_takyon(diagram: Diagram, takyon: Tile, at coord: Coord) -> Diagram {
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let assert Takyon(new_takyons) = takyon
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case { dict.get(diagram, coord) } {
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Ok(Empty) -> dict.insert(diagram, for: coord, insert: takyon)
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Ok(Takyon(existing_takyons)) ->
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dict.insert(
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+
diagram,
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for: coord,
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insert: Takyon(new_takyons + existing_takyons),
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)
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_ -> panic as "I don't think this ever happens"
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}
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}
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+
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pub fn process_row_loop(diagram: Diagram, takyons: List(#(Coord, Tile))) {
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case takyons {
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[takyon, ..rest] -> {
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-
let death_yon = #(takyon.0, takyon.1 + 1)
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+
let death_yon = #(takyon.0.0, takyon.0.1 + 1)
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+
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case dict.get(diagram, death_yon) {
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Ok(Empty) -> {
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process_row_loop(
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-
dict.insert(diagram, for: death_yon, insert: Takyon),
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+
dict.insert(diagram, for: death_yon, insert: takyon.1),
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rest,
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)
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}
···
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process_row_loop(
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diagram
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|> dict.insert(for: death_yon, insert: ActivatedSplitter)
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-
|> dict.insert(
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-
for: #(death_yon.0 - 1, death_yon.1),
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-
insert: Takyon,
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-
)
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-
|> dict.insert(
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for: #(death_yon.0 + 1, death_yon.1),
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insert: Takyon,
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-
),
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+
|> add_takyon(takyon.1, #(death_yon.0 - 1, death_yon.1))
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|> add_takyon(takyon.1, #(death_yon.0 + 1, death_yon.1)),
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rest,
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)
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}
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Ok(Takyon(_)) -> {
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process_row_loop(
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+
diagram
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+
|> add_takyon(takyon.1, death_yon),
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rest,
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)
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}
···
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120
|> list.count(where: fn(x) { x == ActivatedSplitter })
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121
}
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122
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-
pub fn part2(_input) {
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-
todo
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+
pub fn part2(input) {
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let diagram = build_diagram(input)
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let assert Ok(n_rows) =
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+
diagram
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+
|> dict.keys
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|> list.map(fn(x) { x.1 })
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|> list.max(with: int.compare)
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+
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let complete_diagram = oh_shit_im_feeling_it(diagram, list.range(0, n_rows))
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complete_diagram
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|> dict.filter(keeping: fn(key, _) { key.1 == n_rows })
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+
|> dict.values
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+
|> list.map(with: fn(val) {
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case val {
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+
Takyon(n) -> n
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_ -> 0
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+
}
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})
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+
|> int.sum
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}
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pub fn solve() {
+22
test/aoc2025_test.gleam
+22
test/aoc2025_test.gleam
···
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75
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assert day07.part1(input) == 21
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}
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+
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pub fn day07_part2_test() {
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let input =
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+
".......S.......
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+
...............
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+
.......^.......
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+
...............
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+
......^.^......
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+
...............
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+
.....^.^.^.....
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+
...............
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+
....^.^...^....
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+
...............
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+
...^.^...^.^...
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+
...............
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+
..^...^.....^..
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+
...............
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+
.^.^.^.^.^...^.
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+
..............."
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+
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assert day07.part2(input) == 40
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+
}