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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,220 @@ | ||
| use num_integer::lcm; | ||
| use std::collections::{HashMap, HashSet, VecDeque}; | ||
|
|
||
| type Machines<'a> = HashMap<&'a str, (Option<Type>, HashSet<&'a str>)>; | ||
| type Dependencies<'a> = HashMap<&'a str, HashSet<&'a str>>; | ||
|
|
||
| #[derive(Clone, Copy, Debug)] | ||
| enum Type { | ||
| FlipFlop, | ||
| Conjunction, | ||
| } | ||
|
|
||
| #[derive(Clone, Debug)] | ||
| enum State<'a> { | ||
| FlipFlop(bool), | ||
| Conjunction(HashMap<&'a str, bool>), | ||
| } | ||
|
|
||
| impl<'a> State<'a> { | ||
| fn new(key: &'a str, type_: Type, dependencies: &Dependencies<'a>) -> State<'a> { | ||
| match type_ { | ||
| Type::FlipFlop => Self::FlipFlop(false), | ||
| Type::Conjunction => Self::Conjunction(dependencies.get(&key).map_or_else( | ||
| || [].into(), | ||
| |vec| vec.iter().map(|&key| (key, false)).collect(), | ||
| )), | ||
| } | ||
| } | ||
|
|
||
| fn pulse(&mut self, key: &'a str, value: bool) -> Option<bool> { | ||
| match self { | ||
| State::FlipFlop(flip_flop) => { | ||
| if value { | ||
| None | ||
| } else { | ||
| *flip_flop = !*flip_flop; | ||
| Some(*flip_flop) | ||
| } | ||
| } | ||
| State::Conjunction(remembered) => { | ||
| *remembered.get_mut(key)? = value; | ||
| Some(!remembered.iter().all(|(_, &value)| value)) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn value(&self) -> bool { | ||
| match self { | ||
| State::FlipFlop(value) => *value, | ||
| State::Conjunction(remembered) => !remembered.iter().all(|(_, &value)| value), | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn parse(data: &str) -> Option<(Machines, Dependencies)> { | ||
| let mut machines = HashMap::new(); | ||
| let mut dependencies = HashMap::new(); | ||
| for line in data.lines() { | ||
| let Some((lhs, rhs)) = line.split_once(" -> ") else { | ||
| continue; | ||
| }; | ||
| let (key, type_) = if let Some(key) = lhs.strip_prefix('%') { | ||
| (key, Some(Type::FlipFlop)) | ||
| } else if let Some(key) = lhs.strip_prefix('&') { | ||
| (key, Some(Type::Conjunction)) | ||
| } else { | ||
| (lhs, None) | ||
| }; | ||
| let rhs = rhs.split(", ").collect(); | ||
| for &dst in &rhs { | ||
| dependencies | ||
| .entry(dst) | ||
| .or_insert_with(HashSet::new) | ||
| .insert(key); | ||
| } | ||
| machines.insert(key, (type_, rhs)); | ||
| } | ||
| Some((machines, dependencies)) | ||
| } | ||
|
|
||
| pub fn part1(data: &str) -> Option<u32> { | ||
| let (machines, dependencies) = parse(data)?; | ||
| let mut state = machines | ||
| .iter() | ||
| .filter_map(|(&key, (type_, _))| Some((key, State::new(key, (*type_)?, &dependencies)))) | ||
| .collect::<HashMap<_, _>>(); | ||
| let (mut x, mut y) = (0, 0); | ||
| for _ in 0..1000 { | ||
| let mut queue: VecDeque<_> = [("button", "broadcaster", false)].into(); | ||
| while let Some((src, key, value)) = queue.pop_front() { | ||
| if value { | ||
| x += 1; | ||
| } else { | ||
| y += 1 | ||
| } | ||
| let Some(value) = (match state.get_mut(key) { | ||
| Some(state) => state.pulse(src, value), | ||
| None => Some(value), | ||
| }) else { | ||
| continue; | ||
| }; | ||
| let Some((_, dsts)) = machines.get(key) else { | ||
| continue; | ||
| }; | ||
| queue.extend(dsts.iter().map(|&dst| (key, dst, value))); | ||
| } | ||
| } | ||
| Some(x * y) | ||
| } | ||
|
|
||
| pub fn part2(data: &str) -> Option<usize> { | ||
| let (machines, dependencies) = parse(data)?; | ||
| let subsets = dependencies | ||
| .get({ | ||
| let mut iter = dependencies.get("rx")?.iter(); | ||
| let &conjunction = iter.next()?; | ||
| if iter.next().is_some() { | ||
| return None; | ||
| } | ||
| conjunction | ||
| })? | ||
| .iter() | ||
| .map(|&dst| { | ||
| let mut seen = HashSet::new(); | ||
| let mut stack = vec![dst]; | ||
| while let Some(key) = stack.pop() { | ||
| if !seen.insert(key) { | ||
| continue; | ||
| } | ||
| if let Some(keys) = dependencies.get(key) { | ||
| stack.extend(keys); | ||
| }; | ||
| } | ||
| (dst, seen) | ||
| }) | ||
| .collect::<Vec<_>>(); | ||
| for (i, (_, s0)) in subsets.iter().enumerate() { | ||
| for (_, s1) in &subsets[i + 1..] { | ||
| let mut iter = s0.intersection(s1); | ||
| if !iter.next()?.eq(&"broadcaster") || iter.next().is_some() { | ||
| return None; | ||
| } | ||
| } | ||
| } | ||
| subsets.into_iter().try_fold(1, |acc, (_, subset)| { | ||
| let mut state = machines | ||
| .iter() | ||
| .filter_map(|(&key, (type_, _))| { | ||
| if subset.contains(key) { | ||
| Some((key, State::new(key, (*type_)?, &dependencies))) | ||
| } else { | ||
| None | ||
| } | ||
| }) | ||
| .collect::<HashMap<_, _>>(); | ||
| let mut seen = HashMap::new(); | ||
| let size = loop { | ||
| let mut snapshot = state | ||
| .iter() | ||
| .map(|(&key, value)| (key, value.value())) | ||
| .collect::<Vec<_>>(); | ||
| snapshot.sort_by(|(a, _), (b, _)| a.cmp(b)); | ||
| let i = seen.len(); | ||
| match seen.entry(snapshot) { | ||
| std::collections::hash_map::Entry::Occupied(entry) => { | ||
| break Some(i - *entry.get()); | ||
| } | ||
| std::collections::hash_map::Entry::Vacant(entry) => { | ||
| entry.insert(i); | ||
| } | ||
| } | ||
| let mut queue: VecDeque<_> = [("button", "broadcaster", false)].into(); | ||
| while let Some((src, key, value)) = queue.pop_front() { | ||
| let Some(value) = (match state.get_mut(key) { | ||
| Some(state) => state.pulse(src, value), | ||
| None => Some(value), | ||
| }) else { | ||
| continue; | ||
| }; | ||
| let Some((_, dsts)) = machines.get(key) else { | ||
| continue; | ||
| }; | ||
| queue.extend(dsts.intersection(&subset).map(|&dst| (key, dst, value))); | ||
| } | ||
| }?; | ||
| Some(lcm(acc, size)) | ||
| }) | ||
| } | ||
|
|
||
| #[cfg(test)] | ||
| mod tests { | ||
| use super::*; | ||
| use indoc::indoc; | ||
| use pretty_assertions::assert_eq; | ||
|
|
||
| static EXAMPLE_1: &str = indoc! {" | ||
| broadcaster -> a, b, c | ||
| %a -> b | ||
| %b -> c | ||
| %c -> inv | ||
| &inv -> a | ||
| "}; | ||
| static EXAMPLE_2: &str = indoc! {" | ||
| broadcaster -> a | ||
| %a -> inv, con | ||
| &inv -> b | ||
| %b -> con | ||
| &con -> output | ||
| "}; | ||
|
|
||
| #[test] | ||
| fn part1_examples() { | ||
| assert_eq!(Some(32000000), part1(EXAMPLE_1)); | ||
| assert_eq!(Some(11687500), part1(EXAMPLE_2)); | ||
| } | ||
|
|
||
| #[test] | ||
| #[ignore] | ||
| fn part2_examples() {} | ||
| } |
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