jonas.tngl.sh
Advent of Code solutions in Rust
feat: day 8 of AoC 2025
+144
-2
+142
aoc_2025/src/day08.rs
+142
aoc_2025/src/day08.rs
···
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use std::num::ParseIntError;
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use aoc_companion::prelude::*;
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use aoc_utils::linalg::{ParseVectorError, Vector};
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use itertools::Itertools as _;
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pub(crate) struct Door {
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boxes: Vec<Vector<i64, 3>>,
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}
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impl<'input> Solution<'input> for Door {
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fn parse(input: &'input str) -> Result<Self, ParseVectorError<ParseIntError>> {
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input
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.lines()
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.map(str::parse)
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.try_collect()
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.map(|boxes| Door { boxes })
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}
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fn part1(&self) -> usize {
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networks(&self.boxes, 1000)
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.iter()
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.counts()
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.into_values()
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.sorted()
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.rev()
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.take(3)
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.product()
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}
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fn part2(&self) -> i64 {
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let (Vector([x1, _, _]), Vector([x2, _, _])) = final_connection(&self.boxes);
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x1 * x2
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}
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}
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fn networks(boxes: &[Vector<i64, 3>], n_connect: usize) -> Vec<usize> {
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boxes
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.iter()
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.enumerate()
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.tuple_combinations()
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.sorted_unstable_by_key(|((_, pi), (_, pj))| (**pi - **pj).norm_l2_sq())
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.take(n_connect)
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.fold(
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(0..boxes.len()).collect_vec(),
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|mut assoc, ((i, _), (j, _))| {
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update_network_associations(&mut assoc, i, j);
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assoc
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},
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)
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}
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fn final_connection(boxes: &[Vector<i64, 3>]) -> (Vector<i64, 3>, Vector<i64, 3>) {
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boxes
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.iter()
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.enumerate()
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.tuple_combinations()
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.sorted_unstable_by_key(|((_, pi), (_, pj))| (**pi - **pj).norm_l2_sq())
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.scan(
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((0..boxes.len()).collect_vec(), boxes.len()),
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|(assoc, n_grp), ((i, pi), (j, pj))| {
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if update_network_associations(assoc, i, j) == UpdateOutcome::NetworksConnected {
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*n_grp -= 1;
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}
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Some(((*pi, *pj), *n_grp))
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},
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)
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.find(|(_, n_grp)| *n_grp == 1)
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.expect("at least 2 junction boxes should be present")
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.0
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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enum UpdateOutcome {
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AlreadyConnected,
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NetworksConnected,
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}
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fn update_network_associations(assoc: &mut [usize], i: usize, j: usize) -> UpdateOutcome {
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let lhs = assoc[i];
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let rhs = assoc[j];
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if lhs != rhs {
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assoc
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.iter_mut()
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.filter(|x| **x == rhs)
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.for_each(|x| *x = lhs);
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UpdateOutcome::NetworksConnected
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} else {
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UpdateOutcome::AlreadyConnected
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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const EXAMPLE_BOXES: &[Vector<i64, 3>] = &[
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Vector([162, 817, 812]),
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Vector([57, 618, 57]),
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Vector([906, 360, 560]),
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Vector([592, 479, 940]),
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Vector([352, 342, 300]),
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Vector([466, 668, 158]),
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Vector([542, 29, 236]),
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Vector([431, 825, 988]),
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Vector([739, 650, 466]),
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Vector([52, 470, 668]),
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Vector([216, 146, 977]),
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Vector([819, 987, 18]),
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Vector([117, 168, 530]),
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Vector([805, 96, 715]),
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Vector([346, 949, 466]),
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Vector([970, 615, 88]),
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Vector([941, 993, 340]),
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Vector([862, 61, 35]),
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Vector([984, 92, 344]),
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Vector([425, 690, 689]),
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];
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#[test]
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fn example_network_counts() {
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itertools::assert_equal(
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networks(EXAMPLE_BOXES, 10)
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.iter()
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.counts()
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.into_values()
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.sorted()
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.rev(),
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[5, 4, 2, 2, 1, 1, 1, 1, 1, 1, 1],
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);
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}
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#[test]
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fn example_final_connection() {
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assert_eq!(
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final_connection(EXAMPLE_BOXES),
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(Vector([216, 146, 977]), Vector([117, 168, 530]))
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)
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}
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}
+2
-2
aoc_2025/src/main.rs
+2
-2
aoc_2025/src/main.rs
···
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mod day05;
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mod day06;
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mod day07;
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-
// mod day08;
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mod day08;
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// mod day09;
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// mod day10;
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// mod day11;
···
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door!(2025-12-05 ~> day05),
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door!(2025-12-06 ~> day06),
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door!(2025-12-07 ~> day07),
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-
// door!(2025-12-08 ~> day08),
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door!(2025-12-08 ~> day08),
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// door!(2025-12-09 ~> day09),
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// door!(2025-12-10 ~> day10),
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// door!(2025-12-11 ~> day11),