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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,189 @@ | ||
| use std::collections::BTreeSet; | ||
| use std::ops::IndexMut; | ||
|
|
||
| type YX = (usize, usize); | ||
|
|
||
| fn parse(data: &str) -> Option<(Vec<Vec<u8>>, YX, &str)> { | ||
| let (map, moves) = data.split_once("\n\n").unwrap_or((data, "")); | ||
| let map = map | ||
| .lines() | ||
| .map(|line| line.bytes().collect()) | ||
| .collect::<Vec<Vec<_>>>(); | ||
| let robot = map.iter().enumerate().find_map(|(y, line)| { | ||
| line.iter() | ||
| .enumerate() | ||
| .find(|(_, b)| **b == b'@') | ||
| .map(|(x, _)| (y, x)) | ||
| }); | ||
| Some((map, robot?, moves)) | ||
| } | ||
|
|
||
| fn move_robot<Line>(map: &mut [Line], robot: YX, c: char) -> Option<YX> | ||
| where | ||
| Line: IndexMut<usize, Output = u8>, | ||
| { | ||
| let (dy, dx) = match c { | ||
| '^' => (usize::MAX, 0), | ||
| 'v' => (1, 0), | ||
| '<' => (0, usize::MAX), | ||
| '>' => (0, 1), | ||
| _ => return None, | ||
| }; | ||
| let mut levels = vec![]; | ||
| let mut front: BTreeSet<_> = [robot].into(); | ||
| while !front.is_empty() { | ||
| let back = front; | ||
| front = BTreeSet::new(); | ||
| for (y, x) in &back { | ||
| let (y, x) = (y.wrapping_add(dy), x.wrapping_add(dx)); | ||
| match map[y][x] { | ||
| b'.' => continue, | ||
| b'O' => { | ||
| front.insert((y, x)); | ||
| } | ||
| b'[' => { | ||
| front.insert((y, x)); | ||
| if dy != 0 { | ||
| front.insert((y, x + 1)); | ||
| } | ||
| } | ||
| b']' => { | ||
| front.insert((y, x)); | ||
| if dy != 0 { | ||
| front.insert((y, x - 1)); | ||
| } | ||
| } | ||
| _ => return None, | ||
| } | ||
| } | ||
| levels.push(back); | ||
| } | ||
| for front in levels.into_iter().rev() { | ||
| for (y, x) in front { | ||
| map[y.wrapping_add(dy)][x.wrapping_add(dx)] = map[y][x]; | ||
| map[y][x] = b'.'; | ||
| } | ||
| } | ||
| Some((robot.0.wrapping_add(dy), robot.1.wrapping_add(dx))) | ||
| } | ||
|
|
||
| pub fn part1(data: &str) -> Option<usize> { | ||
| let (mut map, mut robot, moves) = parse(data)?; | ||
| for c in moves.chars() { | ||
| robot = move_robot(&mut map, robot, c).unwrap_or(robot); | ||
| } | ||
| Some( | ||
| map.into_iter() | ||
| .enumerate() | ||
| .flat_map(|(y, line)| { | ||
| line.into_iter().enumerate().filter_map(move |(x, b)| { | ||
| if b == b'O' { | ||
| Some(100 * y + x) | ||
| } else { | ||
| None | ||
| } | ||
| }) | ||
| }) | ||
| .sum(), | ||
| ) | ||
| } | ||
|
|
||
| pub fn part2(data: &str) -> Option<usize> { | ||
| let (mut map, mut robot, moves) = parse(data)?; | ||
| for line in &mut map { | ||
| *line = line | ||
| .iter() | ||
| .flat_map(|&b| match b { | ||
| b'@' => *b"@.", | ||
| b'O' => *b"[]", | ||
| _ => [b, b], | ||
| }) | ||
| .collect(); | ||
| } | ||
| robot.1 *= 2; | ||
| for c in moves.chars() { | ||
| robot = move_robot(&mut map, robot, c).unwrap_or(robot); | ||
| } | ||
| Some( | ||
| map.into_iter() | ||
| .enumerate() | ||
| .flat_map(|(y, line)| { | ||
| line.into_iter().enumerate().filter_map(move |(x, b)| { | ||
| if b == b'[' { | ||
| Some(100 * y + x) | ||
| } else { | ||
| None | ||
| } | ||
| }) | ||
| }) | ||
| .sum(), | ||
| ) | ||
| } | ||
|
|
||
| #[cfg(test)] | ||
| mod tests { | ||
| use super::*; | ||
| use indoc::indoc; | ||
| use pretty_assertions::assert_eq; | ||
|
|
||
| static EXAMPLE_1: &str = indoc! {" | ||
| ########## | ||
| #..O..O.O# | ||
| #......O.# | ||
| #.OO..O.O# | ||
| #[email protected].# | ||
| #O#..O...# | ||
| #O..O..O.# | ||
| #.OO.O.OO# | ||
| #....O...# | ||
| ########## | ||
| <vv>^<v^>v>^vv^v>v<>v^v<v<^vv<<<^><<><>>v<vvv<>^v^>^<<<><<v<<<v^vv^v>^ | ||
| vvv<<^>^v^^><<>>><>^<<><^vv^^<>vvv<>><^^v>^>vv<>v<<<<v<^v>^<^^>>>^<v<v | ||
| ><>vv>v^v^<>><>>>><^^>vv>v<^^^>>v^v^<^^>v^^>v^<^v>v<>>v^v^<v>v^^<^^vv< | ||
| <<v<^>>^^^^>>>v^<>vvv^><v<<<>^^^vv^<vvv>^>v<^^^^v<>^>vvvv><>>v^<<^^^^^ | ||
| ^><^><>>><>^^<<^^v>>><^<v>^<vv>>v>>>^v><>^v><<<<v>>v<v<v>vvv>^<><<>^>< | ||
| ^>><>^v<><^vvv<^^<><v<<<<<><^v<<<><<<^^<v<^^^><^>>^<v^><<<^>>^v<v^v<v^ | ||
| >^>>^v>vv>^<<^v<>><<><<v<<v><>v<^vv<<<>^^v^>^^>>><<^v>>v^v><^^>>^<>vv^ | ||
| <><^^>^^^<><vvvvv^v<v<<>^v<v>v<<^><<><<><<<^^<<<^<<>><<><^^^>^^<>^>v<> | ||
| ^^>vv<^v^v<vv>^<><v<^v>^^^>>>^^vvv^>vvv<>>>^<^>>>>>^<<^v>^vvv<>^<><<v> | ||
| v^^>>><<^^<>>^v^<v^vv<>v^<<>^<^v^v><^<<<><<^<v><v<>vv>>v><v^<vv<>v^<<^ | ||
| "}; | ||
|
|
||
| static EXAMPLE_2: &str = indoc! {" | ||
| ######## | ||
| #..O.O.# | ||
| ##@.O..# | ||
| #...O..# | ||
| #.#.O..# | ||
| #...O..# | ||
| #......# | ||
| ######## | ||
| <^^>>>vv<v>>v<< | ||
| "}; | ||
|
|
||
| static EXAMPLE_3: &str = indoc! {" | ||
| ####### | ||
| #...#.# | ||
| #.....# | ||
| #..OO@# | ||
| #..O..# | ||
| #.....# | ||
| ####### | ||
| <vv<<^^<<^^ | ||
| "}; | ||
|
|
||
| #[test] | ||
| fn part1_examples() { | ||
| assert_eq!(Some(2028), part1(EXAMPLE_2)); | ||
| assert_eq!(Some(10092), part1(EXAMPLE_1)); | ||
| } | ||
|
|
||
| #[test] | ||
| fn part2_examples() { | ||
| assert_eq!(Some(618), part2(EXAMPLE_3)); | ||
| assert_eq!(Some(9021), part2(EXAMPLE_1)); | ||
| } | ||
| } |
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