day21 working but not fast enough for part 2
This commit is contained in:
Jan-Bulthuis
parent
8e9dc7c388
commit
e570358fa7
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@ -1,6 +1,44 @@
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use aoc_runner_derive::{aoc, aoc_generator};
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use std::iter::once;
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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use aoc_runner_derive::{aoc, aoc_generator};
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use hashbrown::{hash_map::Entry, HashMap};
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#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
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struct Path {
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steps: usize,
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path: [Option<Button>; 6],
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}
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impl Path {
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fn new() -> Self {
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Self {
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steps: 0,
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path: [None, None, None, None, None, None],
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}
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}
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fn push(&mut self, button: Button) {
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self.path[self.steps] = Some(button);
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self.steps += 1;
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}
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fn append(&mut self, other: &Self) {
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for i in 0..other.steps {
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self.push(other.path[i].unwrap());
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}
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}
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}
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impl IntoIterator for Path {
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type Item = Button;
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type IntoIter = std::iter::Flatten<std::array::IntoIter<Option<Button>, 6>>;
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fn into_iter(self) -> Self::IntoIter {
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self.path.into_iter().flatten()
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}
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
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enum Button {
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Directional(DirectionalButton),
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Numeric(NumericButton),
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@ -14,7 +52,7 @@ impl Button {
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}
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}
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fn to(&self, other: &Button) -> Vec<DirectionalButton> {
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fn to(&self, other: &Button) -> (Path, Option<Path>) {
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match (self, other) {
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(Button::Directional(a), Button::Directional(b)) => a.to(b),
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(Button::Numeric(a), Button::Numeric(b)) => a.to(b),
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@ -23,7 +61,7 @@ impl Button {
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}
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
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enum DirectionalButton {
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Up,
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Down,
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@ -43,30 +81,43 @@ impl DirectionalButton {
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}
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}
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fn to(&self, other: &DirectionalButton) -> Vec<DirectionalButton> {
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fn to(&self, other: &DirectionalButton) -> (Path, Option<Path>) {
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let start = self.pos();
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let end = other.pos();
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let mut x = if start.0 < end.0 {
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vec![DirectionalButton::Right; (end.0 - start.0) as usize]
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let mut x = Path::new();
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let mut y = Path::new();
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if start.0 < end.0 {
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(start.0..end.0).for_each(|_| x.push(Button::Directional(DirectionalButton::Right)));
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} else {
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vec![DirectionalButton::Left; (start.0 - end.0) as usize]
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(end.0..start.0).for_each(|_| x.push(Button::Directional(DirectionalButton::Left)));
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};
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let mut y = if start.1 < end.1 {
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vec![DirectionalButton::Down; (end.1 - start.1) as usize]
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if start.1 < end.1 {
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(start.1..end.1).for_each(|_| y.push(Button::Directional(DirectionalButton::Down)));
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} else {
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vec![DirectionalButton::Up; (start.1 - end.1) as usize]
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(end.1..start.1).for_each(|_| y.push(Button::Directional(DirectionalButton::Up)));
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};
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if end.0 == 0 {
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y.append(&mut x);
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y
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if start.0 == 0 && end.1 == 0 {
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x.append(&y);
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x.push(Button::Directional(DirectionalButton::A));
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(x, None)
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} else if end.0 == 0 && start.1 == 0 {
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y.append(&x);
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y.push(Button::Directional(DirectionalButton::A));
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(y, None)
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} else {
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x.append(&mut y);
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x
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x.append(&y);
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x.push(Button::Directional(DirectionalButton::A));
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y.append(&x);
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y.push(Button::Directional(DirectionalButton::A));
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(x, Some(y))
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}
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}
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
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enum NumericButton {
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Number(u8),
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A,
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@ -90,25 +141,39 @@ impl NumericButton {
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}
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}
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fn to(&self, other: &NumericButton) -> Vec<DirectionalButton> {
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fn to(&self, other: &NumericButton) -> (Path, Option<Path>) {
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let start = self.pos();
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let end = other.pos();
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let mut x = if start.0 < end.0 {
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vec![DirectionalButton::Right; (end.0 - start.0) as usize]
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let mut x = Path::new();
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let mut y = Path::new();
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if start.0 < end.0 {
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(start.0..end.0).for_each(|_| x.push(Button::Directional(DirectionalButton::Right)));
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} else {
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vec![DirectionalButton::Left; (start.0 - end.0) as usize]
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(end.0..start.0).for_each(|_| x.push(Button::Directional(DirectionalButton::Left)));
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};
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let mut y = if start.1 < end.1 {
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vec![DirectionalButton::Down; (end.1 - start.1) as usize]
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if start.1 < end.1 {
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(start.1..end.1).for_each(|_| y.push(Button::Directional(DirectionalButton::Down)));
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} else {
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vec![DirectionalButton::Up; (start.1 - end.1) as usize]
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(end.1..start.1).for_each(|_| y.push(Button::Directional(DirectionalButton::Up)));
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};
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if end.1 != 3 {
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y.append(&mut x);
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y
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if start.0 == 0 && end.1 == 3 {
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x.append(&y);
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x.push(Button::Directional(DirectionalButton::A));
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(x, None)
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} else if end.0 == 0 && start.1 == 3 {
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y.append(&x);
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y.push(Button::Directional(DirectionalButton::A));
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(y, None)
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} else {
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x.append(&mut y);
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x
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let x_copy = x;
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x.append(&y);
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x.push(Button::Directional(DirectionalButton::A));
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y.append(&x_copy);
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y.push(Button::Directional(DirectionalButton::A));
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(x, Some(y))
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}
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}
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}
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@ -141,45 +206,56 @@ fn parse(input: &str) -> Input {
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.collect()
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}
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fn shortest_path(num_robots: usize, path: Path) -> usize {
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type Memos = Vec<HashMap<Path, usize>>;
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let mut memos = vec![HashMap::new(); num_robots];
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fn expand(robots: usize, path: Path, memos: &mut Memos) -> usize {
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if robots == 0 {
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return path.steps;
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}
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let pos = match path.path[0].unwrap() {
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Button::Numeric(_) => Button::Numeric(NumericButton::A),
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Button::Directional(_) => Button::Directional(DirectionalButton::A),
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};
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path.into_iter()
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.fold((pos, 0), |acc, next| {
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let pos = acc.0;
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let steps = acc.1;
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let (first, second) = pos.to(&next);
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let expansion = once(Some(first))
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.chain(once(second))
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.flatten()
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.min_by_key(|path| {
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if memos[robots - 1].contains_key(path) {
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memos[robots - 1][path]
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} else {
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let expanded = expand(robots - 1, *path, memos);
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memos[robots - 1].insert(*path, expanded);
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expanded
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}
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})
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.map(|path| expand(robots - 1, path, memos))
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.unwrap();
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(next, steps + expansion)
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})
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.1
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}
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expand(num_robots, path, &mut memos)
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}
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#[aoc(day21, part1)]
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fn part1(input: &Input) -> usize {
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input
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.iter()
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.cloned()
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.map(|instruction| {
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let mut instructions = vec![];
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let mut stack = vec![];
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let num_robots = 3;
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let mut positions = vec![Button::Numeric(NumericButton::A)];
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for _ in 1..num_robots {
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positions.push(Button::Directional(DirectionalButton::A));
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}
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for button in instruction.iter().rev() {
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stack.push((0, *button));
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}
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while let Some((robot, button)) = stack.pop() {
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if robot == num_robots {
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instructions.push(button);
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continue;
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}
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println!(
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"move {} from {:?} to {:?} = {:?}",
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robot,
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positions[robot].pos(),
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button.pos(),
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button
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);
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let instructions = positions[robot].to(&button);
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stack.push((robot + 1, Button::Directional(DirectionalButton::A)));
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for instruction in instructions.iter().rev() {
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stack.push((robot + 1, Button::Directional(*instruction)));
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}
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positions[robot] = button;
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}
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let numeric = instruction
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.iter()
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.filter_map(|button| match button {
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@ -193,30 +269,44 @@ fn part1(input: &Input) -> usize {
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.parse::<usize>()
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.unwrap();
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dbg!(instructions.len());
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println!(
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"{}",
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instructions
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.iter()
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.map(|instruction| match instruction {
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Button::Directional(DirectionalButton::Up) => '^',
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Button::Directional(DirectionalButton::Down) => 'v',
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Button::Directional(DirectionalButton::Left) => '<',
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Button::Directional(DirectionalButton::Right) => '>',
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Button::Directional(DirectionalButton::A) => 'A',
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_ => unreachable!(),
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})
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.collect::<String>()
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);
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numeric * instructions.len()
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let mut path = Path::new();
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instruction.iter().for_each(|step| path.push(*step));
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let path = shortest_path(3, path);
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numeric * path
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})
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.sum()
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}
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// #[aoc(day21, part2)]
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// fn part2(input: &Input) -> usize {
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// todo!()
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// }
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#[aoc(day21, part2)]
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fn part2(input: &Input) -> usize {
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input
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.iter()
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.cloned()
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.map(|instruction| {
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let numeric = instruction
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.iter()
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.filter_map(|button| match button {
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Button::Numeric(NumericButton::Number(numeric)) => Some(numeric),
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_ => None,
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})
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.fold(String::new(), |mut acc, num| {
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acc.push_str(&num.to_string());
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acc
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})
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.parse::<usize>()
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.unwrap();
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let mut path = Path::new();
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instruction.iter().for_each(|step| path.push(*step));
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let path = shortest_path(8, path);
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numeric * path
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})
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.sum()
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}
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#[cfg(test)]
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mod tests {
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@ -224,7 +314,7 @@ mod tests {
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#[test]
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fn part1_example() {
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// assert_eq!(part1(&parse("179A")), 68 * 179);
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assert_eq!(part1(&parse("179A")), 68 * 179);
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assert_eq!(part1(&parse("379A")), 64 * 379);
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assert_eq!(part1(&parse("456A")), 64 * 456);
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assert_eq!(part1(&parse("980A")), 60 * 980);
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