generated from janezicmatej/aoc-template
89 lines
2.2 KiB
Rust
89 lines
2.2 KiB
Rust
use std::collections::BTreeSet;
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use hashbrown::{HashMap, HashSet};
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use itertools::Itertools;
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fn parse_graph(input: &str) -> HashMap<&str, BTreeSet<&str>> {
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let nodes: HashSet<_> = input.lines().filter_map(|x| x.split_once('-')).collect();
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let mut graph: HashMap<_, BTreeSet<_>> = HashMap::new();
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for (n1, n2) in nodes.iter().copied() {
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graph.entry(n1).or_default().insert(n2);
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graph.entry(n2).or_default().insert(n1);
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}
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graph
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}
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pub fn part_one(input: &str) -> Option<usize> {
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let graph = parse_graph(input);
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let mut triples = HashSet::new();
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for (n1, neigh) in graph.iter() {
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for n2 in neigh.iter().copied() {
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for n3 in graph[n2].iter() {
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if graph[n3].contains(n1) && n1.starts_with('t') {
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let mut triple = [n1, n2, n3];
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triple.sort();
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triples.insert(triple);
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}
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}
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}
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}
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triples.len().into()
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}
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pub fn part_two(input: &str) -> Option<String> {
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let graph = parse_graph(input);
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let p: BTreeSet<_> = graph.keys().copied().collect();
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let r = HashSet::new();
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let x = BTreeSet::new();
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let mut maximals = HashSet::new();
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let mut stack = Vec::new();
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stack.push((r, p, x));
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while let Some((r, mut p, mut x)) = stack.pop() {
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if p.is_empty() && x.is_empty() {
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let mut password = r.iter().copied().collect_vec();
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password.sort();
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maximals.insert(password.join(","));
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}
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while let Some(pp) = p.pop_last() {
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let mut nr = r.clone();
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nr.insert(pp);
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let np = &p & &graph[pp];
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let nx = &x & &graph[pp];
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stack.push((nr, np, nx));
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x.insert(pp);
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}
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}
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maximals.into_iter().max_by_key(|x| x.len())
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}
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aoc::solution!(23);
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_part_one() {
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assert_eq!(part_one(&aoc::template::read_file("examples", 23)), Some(7));
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}
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#[test]
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fn test_part_two() {
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assert_eq!(
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part_two(&aoc::template::read_file("examples", 23)),
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Some("co,de,ka,ta".to_string())
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);
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}
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}
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