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2 changed files with 185 additions and 202 deletions
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2
aoc_2024/src/day20.rs
View File

@ -42,6 +42,7 @@ fn parse(input: &str) -> Input {
#[aoc(day20, part1)]
fn part1(input: &Input) -> usize {
let start = input.0;
let end = input.1;
let map = &input.2;
#[cfg(not(test))]
@ -123,6 +124,7 @@ fn part1(input: &Input) -> usize {
#[aoc(day20, part2)]
fn part2(input: &Input) -> usize {
let start = input.0;
let end = input.1;
let map = &input.2;
#[cfg(not(test))]

397
aoc_2024/src/day21.rs
View File

@ -1,23 +1,56 @@
use aoc_runner_derive::{aoc, aoc_generator};
#[derive(Debug, PartialEq, Eq)]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Path {
steps: usize,
path: [Option<DirButton>; 6],
}
impl Path {
const fn from(buttons: &[DirButton]) -> Option<Self> {
let steps = buttons.len();
let mut path = [None, None, None, None, None, None];
let mut i = 0;
while i < steps {
path[i] = Some(buttons[i]);
i += 1;
fn new() -> Self {
Self {
steps: 0,
path: [None, None, None, None, None, None],
}
let steps = steps + 1;
path[i] = Some(DirButton::A);
Some(Self { steps, path })
}
fn push(&mut self, button: DirButton) {
self.path[self.steps] = Some(button);
self.steps += 1;
}
fn append(&mut self, other: &Self) {
for i in 0..other.steps {
self.push(other.path[i].unwrap());
}
}
fn reversed(&self) -> Self {
let mut path = [None; 6];
(0..self.steps).for_each(|i| {
path[i] = match self.path[self.steps - i - 1] {
Some(DirButton::Up) => Some(DirButton::Down),
Some(DirButton::Down) => Some(DirButton::Up),
Some(DirButton::Left) => Some(DirButton::Right),
Some(DirButton::Right) => Some(DirButton::Left),
Some(DirButton::A) => Some(DirButton::A),
None => None,
};
});
Self {
steps: self.steps,
path,
}
}
}
impl IntoIterator for Path {
type Item = DirButton;
type IntoIter = std::iter::Flatten<std::array::IntoIter<Option<DirButton>, 6>>;
fn into_iter(self) -> Self::IntoIter {
self.path.into_iter().flatten()
}
}
@ -30,94 +63,18 @@ enum DirButton {
A,
}
const DIRBUTTON_PATHS: [[[Option<Path>; 2]; 5]; 5] = [
// Up
[
// Up
[Path::from(&[]), None],
// Down
[Path::from(&[DirButton::Down]), None],
// Left
[Path::from(&[DirButton::Down, DirButton::Left]), None],
// Right
[
Path::from(&[DirButton::Down, DirButton::Right]),
Path::from(&[DirButton::Right, DirButton::Down]),
],
// A
[Path::from(&[DirButton::Right]), None],
],
// Down
[
// Up
[Path::from(&[DirButton::Up]), None],
// Down
[Path::from(&[]), None],
// Left
[Path::from(&[DirButton::Left]), None],
// Right
[Path::from(&[DirButton::Right]), None],
// A
[
Path::from(&[DirButton::Up, DirButton::Right]),
Path::from(&[DirButton::Right, DirButton::Up]),
],
],
// Left
[
// Up
[Path::from(&[DirButton::Right, DirButton::Up]), None],
// Down
[Path::from(&[DirButton::Right]), None],
// Left
[Path::from(&[]), None],
// Right
[Path::from(&[DirButton::Right, DirButton::Right]), None],
// A
[
Path::from(&[DirButton::Right, DirButton::Right, DirButton::Up]),
None,
],
],
// Right
[
// Up
[
Path::from(&[DirButton::Up, DirButton::Left]),
Path::from(&[DirButton::Left, DirButton::Up]),
],
// Down
[Path::from(&[DirButton::Left]), None],
// Left
[Path::from(&[DirButton::Left, DirButton::Left]), None],
// Right
[Path::from(&[]), None],
// A
[Path::from(&[DirButton::Up]), None],
],
// A
[
// Up
[Path::from(&[DirButton::Left]), None],
// Down
[
Path::from(&[DirButton::Down, DirButton::Left]),
Path::from(&[DirButton::Left, DirButton::Down]),
],
// Left
[
Path::from(&[DirButton::Down, DirButton::Left, DirButton::Left]),
None,
],
// Right
[Path::from(&[DirButton::Down]), None],
// A
[Path::from(&[]), None],
],
];
impl DirButton {
const fn index(&self) -> usize {
fn pos(&self) -> (usize, usize) {
match self {
DirButton::Up => (1, 0),
DirButton::Down => (1, 1),
DirButton::Left => (0, 1),
DirButton::Right => (2, 1),
DirButton::A => (2, 0),
}
}
fn index(&self) -> usize {
match self {
DirButton::Up => 0,
DirButton::Down => 1,
@ -127,12 +84,44 @@ impl DirButton {
}
}
const fn paths_to(&self, other: &DirButton) -> &[Option<Path>; 2] {
&DIRBUTTON_PATHS[self.index()][other.index()]
fn to(&self, other: &DirButton) -> [Option<Path>; 2] {
let start = self.pos();
let end = other.pos();
let mut x = Path::new();
let mut y = Path::new();
if start.0 < end.0 {
(start.0..end.0).for_each(|_| x.push(DirButton::Right));
} else {
(end.0..start.0).for_each(|_| x.push(DirButton::Left));
};
if start.1 < end.1 {
(start.1..end.1).for_each(|_| y.push(DirButton::Down));
} else {
(end.1..start.1).for_each(|_| y.push(DirButton::Up));
};
if start.0 == 0 && end.1 == 0 {
x.append(&y);
x.push(DirButton::A);
[Some(x), None]
} else if end.0 == 0 && start.1 == 0 {
y.append(&x);
y.push(DirButton::A);
[Some(y), None]
} else {
let x_copy = x;
x.append(&y);
x.push(DirButton::A);
y.append(&x_copy);
y.push(DirButton::A);
[Some(x), Some(y)]
}
}
}
#[derive(Debug, PartialEq, Eq)]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum NumButton {
One,
Two,
@ -148,7 +137,7 @@ enum NumButton {
}
impl NumButton {
const fn pos(&self) -> (usize, usize) {
fn pos(&self) -> (usize, usize) {
match self {
NumButton::One => (0, 2),
NumButton::Two => (1, 2),
@ -164,84 +153,45 @@ impl NumButton {
}
}
fn paths_to(&self, other: &NumButton) -> [Option<Path>; 2] {
#[inline(always)]
fn to(&self, other: &NumButton) -> [Option<Path>; 2] {
let start = self.pos();
let end = other.pos();
let bx = if start.0 < end.0 {
DirButton::Right
} else {
DirButton::Left
};
let dx = start.0.abs_diff(end.0);
let mut x = Path::new();
let mut y = Path::new();
let by = if start.1 < end.1 {
DirButton::Down
if start.0 < end.0 {
(start.0..end.0).for_each(|_| x.push(DirButton::Right));
} else {
DirButton::Up
(end.0..start.0).for_each(|_| x.push(DirButton::Left));
};
if start.1 < end.1 {
(start.1..end.1).for_each(|_| y.push(DirButton::Down));
} else {
(end.1..start.1).for_each(|_| y.push(DirButton::Up));
};
let dy = start.1.abs_diff(end.1);
if start.0 == 0 && end.1 == 3 {
let mut x = [None, None, None, None, None, None];
(0..dx).for_each(|i| {
x[i] = Some(bx);
});
(0..dy).for_each(|i| {
x[i + dx] = Some(by);
});
x[dx + dy] = Some(DirButton::A);
[
Some(Path {
steps: dx + dy + 1,
path: x,
}),
None,
]
x.append(&y);
x.push(DirButton::A);
[Some(x), None]
} else if end.0 == 0 && start.1 == 3 {
let mut y = [None, None, None, None, None, None];
(0..dx).for_each(|i| {
y[i + dy] = Some(bx);
});
(0..dy).for_each(|i| {
y[i] = Some(by);
});
y[dx + dy] = Some(DirButton::A);
[
Some(Path {
steps: dx + dy + 1,
path: y,
}),
None,
]
y.append(&x);
y.push(DirButton::A);
[Some(y), None]
} else {
let mut x = [None, None, None, None, None, None];
let mut y = [None, None, None, None, None, None];
(0..dx).for_each(|i| {
x[i] = Some(bx);
y[i + dy] = Some(bx);
});
(0..dy).for_each(|i| {
x[i + dx] = Some(by);
y[i] = Some(by);
});
x[dx + dy] = Some(DirButton::A);
y[dx + dy] = Some(DirButton::A);
[
Some(Path {
steps: dx + dy + 1,
path: x,
}),
Some(Path {
steps: dx + dy + 1,
path: y,
}),
]
let x_copy = x;
x.append(&y);
x.push(DirButton::A);
y.append(&x_copy);
y.push(DirButton::A);
[Some(x), Some(y)]
}
}
}
type Input = Vec<(DistanceSize, Vec<NumButton>)>;
type Input = Vec<(usize, Vec<NumButton>)>;
#[aoc_generator(day21)]
fn parse(input: &str) -> Input {
@ -271,8 +221,7 @@ fn parse(input: &str) -> Input {
.collect()
}
type DistanceSize = u64;
type DistanceMatrix = [[DistanceSize; 5]; 5];
type DistanceMatrix = [[usize; 5]; 5];
fn precompute_steps(steps: &mut [DistanceMatrix]) {
if steps.len() == 1 {
@ -289,74 +238,106 @@ fn precompute_steps(steps: &mut [DistanceMatrix]) {
DirButton::A,
];
buttons.iter().for_each(|start| {
buttons.iter().for_each(|end| {
steps[0][start.index()][end.index()] = start
.paths_to(end)
.iter()
buttons.iter().enumerate().for_each(|(i, start)| {
buttons[i + 1..].iter().for_each(|end| {
let (forward, reversed) = start
.to(end)
.into_iter()
.flatten()
.map(|path| {
path.path
.iter()
.flatten()
.fold((0, &DirButton::A), |acc, next| {
(acc.0 + steps[1][acc.1.index()][next.index()], next)
})
.0
})
.fold(DistanceSize::MAX, |acc, next| acc.min(next));
});
});
}
.map(|mut path| {
path.steps -= 1;
let mut reversed = path.reversed();
let mut forward = path;
reversed.push(DirButton::A);
forward.push(DirButton::A);
fn shortest_dir_path(path: Path, steps: &mut [DistanceMatrix]) -> DistanceSize {
path.path
.iter()
.flatten()
.fold((0, &DirButton::A), |acc, next| {
(acc.0 + steps[0][acc.1.index()][next.index()], next)
})
.0
}
fn shortest_path(path: &[NumButton], steps: &mut [DistanceMatrix]) -> DistanceSize {
path.iter()
.fold((0, &NumButton::A), |acc, end| {
(
acc.0
+ acc
.1
.paths_to(end)
forward
.path
.into_iter()
.flatten()
.fold((0, DirButton::A), |acc, next| {
let extension = steps[1][acc.1.index()][next.index()];
(acc.0 + extension, next)
})
.0,
reversed
.path
.into_iter()
.flatten()
.fold((0, DirButton::A), |acc, next| {
let extension = steps[1][acc.1.index()][next.index()];
(acc.0 + extension, next)
})
.0,
)
})
.fold((usize::MAX, usize::MAX), |acc, next| {
(acc.0.min(next.0), acc.1.min(next.1))
});
steps[0][start.index()][end.index()] = forward;
steps[0][end.index()][start.index()] = reversed;
});
});
}
fn shortest_dir_path(path: Path, steps: &mut [DistanceMatrix]) -> usize {
path.path
.into_iter()
.flatten()
.fold((0, DirButton::A), |acc, next| {
let sum = acc.0;
let pos = acc.1;
let extension = steps[0][pos.index()][next.index()];
(sum + extension, next)
})
.0
}
fn shortest_path(path: Vec<NumButton>, steps: &mut [DistanceMatrix]) -> usize {
path.into_iter()
.fold((0, NumButton::A), |acc, end| {
let sum = acc.0;
let start = acc.1;
let extension = start
.to(&end)
.into_iter()
.flatten()
.map(|path| shortest_dir_path(path, steps))
.fold(DistanceSize::MAX, |acc, next| acc.min(next)),
end,
)
.min()
.unwrap();
(sum + extension, end)
})
.0
}
#[aoc(day21, part1)]
fn part1(input: &Input) -> DistanceSize {
fn part1(input: &Input) -> usize {
let mut steps = vec![[[1; 5]; 5]; 3];
precompute_steps(&mut steps);
input
.iter()
.cloned()
.map(|(num, path)| num * shortest_path(path, &mut steps))
.sum()
}
#[aoc(day21, part2)]
fn part2(input: &Input) -> DistanceSize {
fn part2(input: &Input) -> usize {
let mut steps = vec![[[1; 5]; 5]; 26];
precompute_steps(&mut steps);
input
.iter()
.cloned()
.map(|(num, path)| num * shortest_path(path, &mut steps))
.sum()
}