diff --git a/2021/benches/days.rs b/2021/benches/days.rs index 7c65473..053d0fa 100644 --- a/2021/benches/days.rs +++ b/2021/benches/days.rs @@ -7,7 +7,7 @@ use criterion::criterion_main; use criterion::BenchmarkId; use criterion::Criterion; -const DAYS_IMPLEMENTED: usize = 21; +const DAYS_IMPLEMENTED: usize = 22; fn read_input(day: usize) -> Vec { let input_path = format!("inputs/{:02}.txt", day); diff --git a/2021/src/day11.rs b/2021/src/day11.rs index 2eaadd4..80d7d8b 100644 --- a/2021/src/day11.rs +++ b/2021/src/day11.rs @@ -79,7 +79,7 @@ pub fn part2(input: &mut dyn Read) -> String { let mut grid = read_grid(input, &mut buffer); let mut todo = Vec::new(); - let target = grid.iter().map(|line| line.len()).sum(); + let target: usize = grid.iter().map(|line| line.len()).sum(); (1..) .find(|_| advance(&mut grid, &mut todo) == target) diff --git a/2021/src/day22.rs b/2021/src/day22.rs index dcbe98f..897e51d 100644 --- a/2021/src/day22.rs +++ b/2021/src/day22.rs @@ -1,5 +1,4 @@ use std::io::Read; -use std::ops::RangeInclusive; use nom::branch::alt; use nom::bytes::complete::tag; @@ -13,78 +12,169 @@ use nom::IResult; use crate::common::read_input; -type CRange = RangeInclusive; +type Point3 = [i32; 3]; -fn parse_range(input: &[u8]) -> IResult<&[u8], CRange> { - use nom::character::complete::i32; - - map(separated_pair(i32, tag(".."), i32), |(first, last)| { - first..=last - })(input) +#[derive(Debug, Eq, PartialEq)] +struct Cuboid { + lower: Point3, + upper: Point3, } -fn parse_input(input: &[u8]) -> IResult<&[u8], Vec<(bool, [CRange; 3])>> { - let parse_state = alt((map(tag("on x="), |_| true), map(tag("off x="), |_| false))); - let parse_line = map( +impl Cuboid { + pub fn new(lower: Point3, upper: Point3) -> Self { + // The input uses an inclusive range for representation, but an exclusive one simplifies a + // lot of computations, so we convert here. + Self::new_internal(lower, upper.map(|c| c + 1)) + } + + fn new_internal(lower: Point3, upper: Point3) -> Self { + debug_assert!(lower.iter().zip(&upper).all(|(a, b)| a < b)); + Self { lower, upper } + } + + pub fn is_small(&self) -> bool { + self.lower + .iter() + .chain(&self.upper.map(|c| c - 1)) // begrudgingly convert back + .all(|c| c.abs() <= 50) + } + + pub fn volume(&self) -> i64 { + self.lower + .iter() + .zip(&self.upper) + .map(|(&l, &h)| (h - l) as i64) + .product() + } + + fn overlaps(&self, other: &Self) -> bool { + self.lower + .iter() + .zip(&self.upper) + .zip(other.lower.iter().zip(&other.upper)) + .all(|((&al, &ah), (&bl, &bh))| al < bh && bl < ah) + } + + pub fn retain_nonoverlapping(&self, other: &Self, new_cubes: &mut Vec) -> bool { + if !self.overlaps(other) { + // Cube can be kept as-is. + return true; + } + + if other.lower[0] > self.lower[0] { + // We have a set of X-coordinates below the overlap, add a cube for that + new_cubes.push(Self::new_internal( + self.lower, + [other.lower[0], self.upper[1], self.upper[2]], + )); + } + + if other.upper[0] < self.upper[0] { + // Similarly, we can remove an upper section. + new_cubes.push(Self::new_internal( + [other.upper[0], self.lower[1], self.lower[2]], + self.upper, + )); + } + + // Now we can fix the X-coordinates of the overlap section + let overlap_xl = self.lower[0].max(other.lower[0]); + let overlap_xh = self.upper[0].min(other.upper[0]); + + // Same strategy for the Y axis + if other.lower[1] > self.lower[1] { + new_cubes.push(Self::new_internal( + [overlap_xl, self.lower[1], self.lower[2]], + [overlap_xh, other.lower[1], self.upper[2]], + )) + } + if other.upper[1] < self.upper[1] { + new_cubes.push(Self::new_internal( + [overlap_xl, other.upper[1], self.lower[2]], + [overlap_xh, self.upper[1], self.upper[2]], + )) + } + + let overlap_yl = self.lower[1].max(other.lower[1]); + let overlap_yh = self.upper[1].min(other.upper[1]); + + // Finally, handle the last axis + if other.lower[2] > self.lower[2] { + new_cubes.push(Self::new_internal( + [overlap_xl, overlap_yl, self.lower[2]], + [overlap_xh, overlap_yh, other.lower[2]], + )) + } + if other.upper[2] < self.upper[2] { + new_cubes.push(Self::new_internal( + [overlap_xl, overlap_yl, other.upper[2]], + [overlap_xh, overlap_yh, self.upper[2]], + )) + } + + false + } +} + +fn parse_tuple(input: &[u8]) -> IResult<&[u8], (i32, i32)> { + use nom::character::complete::i32; + separated_pair(i32, tag(".."), i32)(input) +} + +fn parse_cuboid(input: &[u8]) -> IResult<&[u8], Cuboid> { + map( tuple(( - parse_state, - parse_range, - preceded(tag(",y="), parse_range), - preceded(tag(",z="), parse_range), + parse_tuple, + preceded(tag(",y="), parse_tuple), + preceded(tag(",z="), parse_tuple), )), - |(b, x, y, z)| (b, [x, y, z]), - ); + |((xl, xh), (yl, yh), (zl, zh))| Cuboid::new([xl, yl, zl], [xh, yh, zh]), + )(input) +} + +fn parse_input(input: &[u8]) -> IResult<&[u8], Vec<(bool, Cuboid)>> { + let parse_state = alt((map(tag("on x="), |_| true), map(tag("off x="), |_| false))); + let parse_line = tuple((parse_state, parse_cuboid)); separated_list1(newline, parse_line)(input) } pub fn part1(input: &mut dyn Read) -> String { - const MAX_ABS_VAL: i32 = 50; - const SIDE_LEN: usize = 2 * (MAX_ABS_VAL as usize) + 1; + let commands = read_input(input, parse_input); + let mut cubes = Vec::new(); + let mut new_cubes = Vec::new(); - let mut state = [[0u128; SIDE_LEN]; SIDE_LEN]; + for (state, cube) in commands.into_iter().filter(|(_, c)| c.is_small()) { + cubes.retain(|existing: &Cuboid| existing.retain_nonoverlapping(&cube, &mut new_cubes)); - let valid_range = -MAX_ABS_VAL..=MAX_ABS_VAL; + // Add new cubes to the end + cubes.append(&mut new_cubes); - let ranges = read_input(input, parse_input); - - for (toggle, [xr, yr, zr]) in ranges { - for z in zr { - if !valid_range.contains(&z) { - continue; - } - for y in yr.clone() { - if !valid_range.contains(&y) { - continue; - } - let row = &mut state[(z + MAX_ABS_VAL) as usize][(y + MAX_ABS_VAL) as usize]; - - for x in xr.clone() { - if !valid_range.contains(&x) { - continue; - } - let bit = 1 << (x + MAX_ABS_VAL); - - if toggle { - *row |= bit; - } else { - *row &= !bit; - } - } - } + if state { + cubes.push(cube); } } - state - .iter() - .flatten() - .map(|val| val.count_ones()) - .sum::() - .to_string() + cubes.iter().map(Cuboid::volume).sum::().to_string() } -pub fn part2(_input: &mut dyn Read) -> String { - todo!() +pub fn part2(input: &mut dyn Read) -> String { + let commands = read_input(input, parse_input); + let mut cubes = Vec::new(); + let mut new_cubes = Vec::new(); + + for (state, cube) in commands { + cubes.retain(|existing: &Cuboid| existing.retain_nonoverlapping(&cube, &mut new_cubes)); + + // Add new cubes to the end + cubes.append(&mut new_cubes); + + if state { + cubes.push(cube); + } + } + + cubes.iter().map(Cuboid::volume).sum::().to_string() } #[cfg(test)] @@ -93,15 +183,39 @@ mod tests { use super::*; - const SAMPLE: &[u8] = include_bytes!("samples/22.txt"); + const SAMPLE1: &[u8] = include_bytes!("samples/22.1.txt"); + const SAMPLE2: &[u8] = include_bytes!("samples/22.2.txt"); + + #[test] + fn test_overlap() { + let cube_a = Cuboid { + lower: [1, 1, 1], + upper: [4, 4, 4], + }; + + let cube_b = Cuboid { + lower: [2, 2, 2], + upper: [3, 3, 3], + }; + + let mut new_cubes = Vec::new(); + + // B is fully inside A so it should overlap and the result should be empty + assert!(!cube_b.retain_nonoverlapping(&cube_a, &mut new_cubes)); + assert_eq!(new_cubes, Vec::new()); + + // In the reverse case, we should have lots of new cubes + assert!(!cube_a.retain_nonoverlapping(&cube_b, &mut new_cubes)); + assert_eq!(new_cubes.len(), 6); + } #[test] fn sample_part1() { - test_implementation(part1, SAMPLE, 590784); + test_implementation(part1, SAMPLE1, 590784); } #[test] fn sample_part2() { - // test_implementation(part2, SAMPLE, 230) + test_implementation(part2, SAMPLE2, 2758514936282235u64); } } diff --git a/2021/src/lib.rs b/2021/src/lib.rs index 8dd9e94..a1a530a 100644 --- a/2021/src/lib.rs +++ b/2021/src/lib.rs @@ -92,7 +92,7 @@ pub fn get_implementation(day: usize, part2: bool) -> Solution { #[cfg(test)] fn test_implementation(solution: Solution, data: &[u8], answer: impl ToString) { - let result = solution(&mut data.as_ref()); + let result = solution(&mut &data[..]); assert_eq!(answer.to_string(), result); } diff --git a/2021/src/samples/22.txt b/2021/src/samples/22.1.txt similarity index 100% rename from 2021/src/samples/22.txt rename to 2021/src/samples/22.1.txt diff --git a/2021/src/samples/22.2.txt b/2021/src/samples/22.2.txt new file mode 100644 index 0000000..aba7585 --- /dev/null +++ b/2021/src/samples/22.2.txt @@ -0,0 +1,60 @@ +on x=-5..47,y=-31..22,z=-19..33 +on x=-44..5,y=-27..21,z=-14..35 +on x=-49..-1,y=-11..42,z=-10..38 +on x=-20..34,y=-40..6,z=-44..1 +off x=26..39,y=40..50,z=-2..11 +on x=-41..5,y=-41..6,z=-36..8 +off x=-43..-33,y=-45..-28,z=7..25 +on x=-33..15,y=-32..19,z=-34..11 +off x=35..47,y=-46..-34,z=-11..5 +on x=-14..36,y=-6..44,z=-16..29 +on x=-57795..-6158,y=29564..72030,z=20435..90618 +on x=36731..105352,y=-21140..28532,z=16094..90401 +on x=30999..107136,y=-53464..15513,z=8553..71215 +on x=13528..83982,y=-99403..-27377,z=-24141..23996 +on x=-72682..-12347,y=18159..111354,z=7391..80950 +on x=-1060..80757,y=-65301..-20884,z=-103788..-16709 +on x=-83015..-9461,y=-72160..-8347,z=-81239..-26856 +on x=-52752..22273,y=-49450..9096,z=54442..119054 +on x=-29982..40483,y=-108474..-28371,z=-24328..38471 +on x=-4958..62750,y=40422..118853,z=-7672..65583 +on x=55694..108686,y=-43367..46958,z=-26781..48729 +on x=-98497..-18186,y=-63569..3412,z=1232..88485 +on x=-726..56291,y=-62629..13224,z=18033..85226 +on x=-110886..-34664,y=-81338..-8658,z=8914..63723 +on x=-55829..24974,y=-16897..54165,z=-121762..-28058 +on x=-65152..-11147,y=22489..91432,z=-58782..1780 +on x=-120100..-32970,y=-46592..27473,z=-11695..61039 +on x=-18631..37533,y=-124565..-50804,z=-35667..28308 +on x=-57817..18248,y=49321..117703,z=5745..55881 +on x=14781..98692,y=-1341..70827,z=15753..70151 +on x=-34419..55919,y=-19626..40991,z=39015..114138 +on x=-60785..11593,y=-56135..2999,z=-95368..-26915 +on x=-32178..58085,y=17647..101866,z=-91405..-8878 +on x=-53655..12091,y=50097..105568,z=-75335..-4862 +on x=-111166..-40997,y=-71714..2688,z=5609..50954 +on x=-16602..70118,y=-98693..-44401,z=5197..76897 +on x=16383..101554,y=4615..83635,z=-44907..18747 +off x=-95822..-15171,y=-19987..48940,z=10804..104439 +on x=-89813..-14614,y=16069..88491,z=-3297..45228 +on x=41075..99376,y=-20427..49978,z=-52012..13762 +on x=-21330..50085,y=-17944..62733,z=-112280..-30197 +on x=-16478..35915,y=36008..118594,z=-7885..47086 +off x=-98156..-27851,y=-49952..43171,z=-99005..-8456 +off x=2032..69770,y=-71013..4824,z=7471..94418 +on x=43670..120875,y=-42068..12382,z=-24787..38892 +off x=37514..111226,y=-45862..25743,z=-16714..54663 +off x=25699..97951,y=-30668..59918,z=-15349..69697 +off x=-44271..17935,y=-9516..60759,z=49131..112598 +on x=-61695..-5813,y=40978..94975,z=8655..80240 +off x=-101086..-9439,y=-7088..67543,z=33935..83858 +off x=18020..114017,y=-48931..32606,z=21474..89843 +off x=-77139..10506,y=-89994..-18797,z=-80..59318 +off x=8476..79288,y=-75520..11602,z=-96624..-24783 +on x=-47488..-1262,y=24338..100707,z=16292..72967 +off x=-84341..13987,y=2429..92914,z=-90671..-1318 +off x=-37810..49457,y=-71013..-7894,z=-105357..-13188 +off x=-27365..46395,y=31009..98017,z=15428..76570 +off x=-70369..-16548,y=22648..78696,z=-1892..86821 +on x=-53470..21291,y=-120233..-33476,z=-44150..38147 +off x=-93533..-4276,y=-16170..68771,z=-104985..-24507