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[2024] Day 15 initial solution
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‎README.md

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@@ -19,6 +19,7 @@ Thank you to [Eric Wastl](http://was.tl) for running this incredible yearly even
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- [Day 12: Garden Groups](aoc_2024/src/day_12.rs)
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- [Day 13: Claw Contraption](aoc_2024/src/day_13.rs)
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- [Day 14: Restroom Redoubt](aoc_2024/src/day_14.rs)
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- [Day 15: Warehouse Woes](aoc_2024/src/day_15.rs)
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<!-- MARKER -->
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## [2023](https://adventofcode.com/2023) [![aoc_2023](https://github.com/connorslade/advent-of-code/actions/workflows/aoc_2023.yml/badge.svg)](https://github.com/connorslade/advent-of-code/actions/workflows/aoc_2023.yml)

‎aoc_2024/src/day_15.rs

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use std::fmt::{Debug, Write};
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use aoc_lib::{direction::cardinal::Direction, matrix::Matrix};
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use common::{solution, Answer};
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use nd_vec::{vector, Vec2};
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solution!("Warehouse Woes", 15);
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fn part_a(input: &str) -> Answer {
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let mut problem = Problem::parse(input, false);
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problem.tick_all(false);
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problem.score().into()
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}
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fn part_b(input: &str) -> Answer {
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let mut problem = Problem::parse(input, true);
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problem.tick_all(true);
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problem.score().into()
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}
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struct Problem {
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pos: Vec2<usize>,
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idx: usize,
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board: Matrix<Tile>,
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instructions: Vec<Direction>,
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}
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#[derive(PartialEq, Eq, Clone, Copy)]
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enum Tile {
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Robot,
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Wall,
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Box,
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BoxRight,
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Empty,
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}
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impl Problem {
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fn parse(input: &str, part_b: bool) -> Self {
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let (board, instructions) = input.split_once("\n\n").unwrap();
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let mut board = Matrix::new_chars(board, |chr| match chr {
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'@' => Tile::Robot,
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'#' => Tile::Wall,
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'O' => Tile::Box,
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'.' => Tile::Empty,
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_ => panic!(),
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});
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if part_b {
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board.size = vector!(board.size.x() * 2, board.size.y());
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let mut new = Vec::new();
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for data in board.data {
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new.push(data);
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new.push(match data {
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Tile::Box => Tile::BoxRight,
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Tile::Robot => Tile::Empty,
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_ => data,
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});
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}
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board.data = new;
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}
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let instructions = instructions
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.chars()
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.filter_map(|x| {
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Some(match x {
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'<' => Direction::Left,
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'>' => Direction::Right,
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'^' => Direction::Up,
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'v' => Direction::Down,
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_ => return None,
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})
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})
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.collect::<Vec<_>>();
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let pos = board.find(Tile::Robot).unwrap();
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board.set(pos, Tile::Empty);
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Self {
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pos,
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idx: 0,
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board,
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instructions,
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}
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}
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fn tick_all(&mut self, part_b: bool) {
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for _ in 0..self.instructions.len() {
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self.tick(part_b);
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}
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}
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fn tick(&mut self, part_b: bool) {
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let dir = self.instructions[self.idx];
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self.idx += 1;
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let new = dir.advance(self.pos);
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if {
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if part_b {
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self.push_b(new, dir)
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} else {
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self.push(new, dir)
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}
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} {
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self.pos = new;
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}
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}
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// -> was successful
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fn push(&mut self, pos: Vec2<usize>, dir: Direction) -> bool {
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// if we are air, return true
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let value = self.board[pos];
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match value {
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Tile::Empty => return true,
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Tile::Wall => return false,
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_ => {}
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}
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// if where we want to move is full, try to move that
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let new = dir.wrapping_advance(pos);
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if !self.board.contains(new) {
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return false;
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}
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if self.board[new] == Tile::Empty || self.push(new, dir) {
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self.board.set(new, value);
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self.board.set(pos, Tile::Empty);
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true
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} else {
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false
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}
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}
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fn can_push(&self, pos: Vec2<usize>, dir: Direction) -> bool {
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// println!("{pos:?}, {dir:?}");
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let value = self.board[pos];
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match value {
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Tile::Empty => return true,
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Tile::Wall => return false,
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Tile::Box | Tile::BoxRight => {}
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Tile::Robot => unreachable!(),
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}
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let other_box = match value {
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Tile::Box => pos + vector!(1, 0),
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Tile::BoxRight => pos - vector!(1, 0),
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_ => unreachable!(),
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};
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// if where we want to move is full, try to move that
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let new_a = dir.wrapping_advance(pos);
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let new_b = dir.wrapping_advance(other_box);
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if !(self.board.contains(new_a) && self.board.contains(new_b)) {
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return false;
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}
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(self.board[new_a] == Tile::Empty && self.board[new_b] == Tile::Empty)
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|| ((new_a == other_box || self.can_push(new_a, dir))
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&& (new_b == pos || self.can_push(new_b, dir)))
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}
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fn push_b(&mut self, pos: Vec2<usize>, dir: Direction) -> bool {
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if self.can_push(pos, dir) {
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let value = self.board[pos];
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if value == Tile::Empty {
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return true;
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}
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assert!(matches!(value, Tile::Box | Tile::BoxRight));
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let other_box = match value {
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Tile::Box => pos + vector!(1, 0),
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Tile::BoxRight => pos - vector!(1, 0),
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_ => unreachable!(),
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};
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let other_value = self.board[other_box];
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let new_a = dir.wrapping_advance(pos);
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let new_b = dir.wrapping_advance(other_box);
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if !(self.board.contains(new_a) && self.board.contains(new_b)) {
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return false;
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}
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if (self.board[new_a] == Tile::Empty && self.board[new_b] == Tile::Empty)
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|| ((new_a == other_box || self.push_b(new_a, dir))
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&& (new_b == pos || self.push_b(new_b, dir)))
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{
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// do push
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self.board.set(new_a, value);
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self.board.set(pos, Tile::Empty);
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self.board.set(new_b, other_value);
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if other_box != new_a {
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self.board.set(other_box, Tile::Empty);
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}
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true
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} else {
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false
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}
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} else {
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false
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}
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}
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fn score(&self) -> u32 {
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let mut score = 0;
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for (pos, _) in self.board.iter().filter(|x| *x.1 == Tile::Box) {
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score += (100 * pos.y() + pos.x()) as u32;
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}
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score
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}
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fn debug(&self) {
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let mut dbg = self.board.clone();
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dbg.set(self.pos, Tile::Robot);
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println!("{:?}", dbg);
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}
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}
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impl Debug for Tile {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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match self {
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Tile::Robot => f.write_char('@'),
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Tile::Wall => f.write_char('#'),
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Tile::Box => f.write_char('['),
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Tile::BoxRight => f.write_char(']'),
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Tile::Empty => f.write_char('.'),
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}
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}
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}
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#[cfg(test)]
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mod test {
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use indoc::indoc;
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const CASE: &str = indoc! {"
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##########
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#..O..O.O#
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#......O.#
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#.OO..O.O#
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#..O@..O.#
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#O#..O...#
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#O..O..O.#
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#.OO.O.OO#
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#....O...#
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##########
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<vv>^<v^>v>^vv^v>v<>v^v<v<^vv<<<^><<><>>v<vvv<>^v^>^<<<><<v<<<v^vv^v>^
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vvv<<^>^v^^><<>>><>^<<><^vv^^<>vvv<>><^^v>^>vv<>v<<<<v<^v>^<^^>>>^<v<v
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><>vv>v^v^<>><>>>><^^>vv>v<^^^>>v^v^<^^>v^^>v^<^v>v<>>v^v^<v>v^^<^^vv<
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<<v<^>>^^^^>>>v^<>vvv^><v<<<>^^^vv^<vvv>^>v<^^^^v<>^>vvvv><>>v^<<^^^^^
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^><^><>>><>^^<<^^v>>><^<v>^<vv>>v>>>^v><>^v><<<<v>>v<v<v>vvv>^<><<>^><
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^>><>^v<><^vvv<^^<><v<<<<<><^v<<<><<<^^<v<^^^><^>>^<v^><<<^>>^v<v^v<v^
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>^>>^v>vv>^<<^v<>><<><<v<<v><>v<^vv<<<>^^v^>^^>>><<^v>>v^v><^^>>^<>vv^
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<><^^>^^^<><vvvvv^v<v<<>^v<v>v<<^><<><<><<<^^<<<^<<>><<><^^^>^^<>^>v<>
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^^>vv<^v^v<vv>^<><v<^v>^^^>>>^^vvv^>vvv<>>>^<^>>>>>^<<^v>^vvv<>^<><<v>
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v^^>>><<^^<>>^v^<v^vv<>v^<<>^<^v^v><^<<<><<^<v><v<>vv>>v><v^<vv<>v^<<^
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"};
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#[test]
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fn part_a() {
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assert_eq!(super::part_a(CASE), 10092.into());
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}
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#[test]
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fn part_b() {
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assert_eq!(super::part_b(CASE), 9021.into());
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}
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}

‎aoc_2024/src/lib.rs

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@@ -14,6 +14,7 @@ mod day_11;
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mod day_12;
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mod day_13;
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mod day_14;
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mod day_15;
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// [import_marker]
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pub const SOLUTIONS: &[Solution] = &[
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day_12::SOLUTION,
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day_13::SOLUTION,
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day_14::SOLUTION,
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day_15::SOLUTION,
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// [list_marker]
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];

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