bwc9876.dev
Advent of Code solutions
Day 7
+115
-5
+83
-5
years/2025/src/day_7.rs
+83
-5
years/2025/src/day_7.rs
···
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use std::collections::{HashMap, HashSet, VecDeque};
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use advent_core::{Day, day_stuff, ex_for_day};
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use utils::{dir::Direction, pos::Position, tiles};
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pub struct Day7;
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tiles!(Tile, [
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'S' => Start,
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'^' => Splitter,
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'.' => Empty,
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]);
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type Grid = utils::grid::Grid<Tile>;
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impl Day for Day7 {
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day_stuff!(7, "21", "40", Grid);
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day_stuff!(7, "", "");
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fn part_1(input: Self::Input) -> Option<String> {
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let (start, _) = input.iter().find(|(_, t)| **t == Tile::Start).unwrap();
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let mut queue = VecDeque::<Position>::new();
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let mut seen = HashSet::<Position>::with_capacity(input.size().1);
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queue.push_back(start);
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let mut splits = 0;
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fn part_1(_input: Self::Input) -> Option<String> {
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None
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while let Some(pos) = queue.pop_front() {
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if seen.contains(&pos) {
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continue;
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}
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seen.insert(pos);
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let next_pos = Position::new(pos.x, pos.y + 1);
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match input.get(next_pos) {
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Some(Tile::Splitter) => {
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splits += 1;
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queue.push_back(Position::new(pos.x + 1, pos.y));
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queue.push_back(Position::new(pos.x - 1, pos.y));
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}
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Some(Tile::Empty) => {
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queue.push_back(next_pos);
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}
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_ => {}
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}
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}
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Some(splits.to_string())
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}
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fn part_2(_input: Self::Input) -> Option<String> {
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None
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fn part_2(input: Self::Input) -> Option<String> {
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let (start, _) = input.iter().find(|(_, t)| **t == Tile::Start).unwrap();
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let mut queue = VecDeque::<Position>::new();
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let mut seen = HashMap::<Position, usize>::new();
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seen.insert(start, 1);
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queue.push_front(start);
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let mut splits = 0;
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while let Some(pos) = queue.pop_front() {
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let amnt = seen.get(&pos).copied().unwrap_or_default();
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let next_pos = pos.move_dir(Direction::South);
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match input.get(next_pos) {
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Some(Tile::Splitter) => {
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for (next_pos, _) in next_pos.relatives(&[Direction::West, Direction::East]) {
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if let Some(curr) = seen.get_mut(&next_pos) {
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*curr += amnt;
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} else {
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seen.insert(next_pos, amnt);
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queue.push_back(next_pos);
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}
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}
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}
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Some(Tile::Empty) => {
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if let Some(curr) = seen.get_mut(&next_pos) {
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*curr += amnt;
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} else {
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seen.insert(next_pos, amnt);
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queue.push_back(next_pos);
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}
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}
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None => {
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splits += amnt;
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}
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_ => {}
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}
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}
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Some(splits.to_string())
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}
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fn parse_input(input: &str) -> Self::Input {
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Grid::parse(input)
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}
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}
+16
years/2025/src/examples/day_7/1.txt
+16
years/2025/src/examples/day_7/1.txt
···
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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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...............
+16
years/2025/src/examples/day_7/2.txt
+16
years/2025/src/examples/day_7/2.txt
···
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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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...............