269 lines
8.1 KiB
Rust
269 lines
8.1 KiB
Rust
use grid::*;
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use rayon::prelude::*;
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use std::char;
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use std::collections::{HashMap, HashSet};
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use std::io::{self, BufRead};
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use std::ops::Mul;
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use std::sync::Mutex;
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#[macro_use]
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extern crate lazy_static;
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#[derive(Hash, PartialEq, Eq, Clone, Debug)]
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struct Door(char);
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#[derive(Hash, PartialEq, Eq, Clone, Debug)]
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struct Key(char);
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lazy_static! {
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static ref BEST: Mutex<usize> = Mutex::new(999999);
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}
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fn too_slow(i: usize) -> bool {
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let best = BEST.lock().unwrap();
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*best < i
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}
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fn replace(i: usize) {
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let mut best = BEST.lock().unwrap();
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if i < *best {
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println!("Best so far: {}", i);
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*best = i;
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}
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}
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fn visit_neighbors(
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map: &HashMap<Position2D, char>,
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position: Position2D,
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steps: usize,
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distances: &mut HashMap<Position2D, usize>,
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dependencies: &mut HashMap<Key, (HashSet<Key>, HashSet<Door>)>,
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door_dependencies: &mut HashMap<Door, HashSet<Door>>,
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mut doors: HashSet<Door>,
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mut keys: HashSet<Key>,
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) {
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let c = map.get(&position).unwrap();
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if c.is_alphabetic() {
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if c.is_lowercase() {
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dependencies.insert(Key { 0: *c }, (keys.clone(), doors.clone()));
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keys.insert(Key { 0: *c });
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}
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if c.is_uppercase() {
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door_dependencies.insert(Door { 0: *c }, doors.clone());
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doors.insert(Door { 0: *c });
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}
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}
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let mut unvisited = Vec::new();
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// TODO: fix ownership and make this a single filter().inspect().for_each()
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for (_, p) in &position.neighbors() {
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match map.get(p) {
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Some('#') => (),
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_ => {
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if distances.get(p).is_none() {
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unvisited.push(p.to_owned());
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}
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}
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}
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if map.get(p) != Some(&'#') && distances.get(p).is_none() {
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unvisited.push(p.to_owned());
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}
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}
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/*
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unvisited.into_iter()
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.inspect(|p| { distances.insert(p.to_owned(), steps+1);})
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.for_each(|p| visit_neighbors(p.to_owned(), steps+1, distances));
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*/
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for p in &unvisited {
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distances.insert(p.to_owned(), steps + 1);
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}
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for p in &unvisited {
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visit_neighbors(
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map,
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p.to_owned(),
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steps + 1,
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distances,
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dependencies,
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door_dependencies,
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doors.clone(),
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keys.clone(),
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);
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}
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}
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fn traverse(
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map: &HashMap<Position2D, char>,
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start: Position2D,
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) -> (
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HashMap<Position2D, usize>,
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HashMap<Key, (HashSet<Key>, HashSet<Door>)>,
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HashMap<Door, HashSet<Door>>,
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) {
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let mut distances = HashMap::new();
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let mut dependencies = HashMap::new();
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let mut door_dependencies = HashMap::new();
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distances.insert(start, 0usize);
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visit_neighbors(
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map,
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start,
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0,
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&mut distances,
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&mut dependencies,
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&mut door_dependencies,
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HashSet::new(),
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HashSet::new(),
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);
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(distances, dependencies, door_dependencies)
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}
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fn find_keys_at_dead_ends(deps: &HashMap<Key, (HashSet<Key>, HashSet<Door>)>) -> HashSet<Key> {
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let keydeps: HashSet<_> = deps.iter().flat_map(|(_, (keys, _))| keys).collect();
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deps.keys()
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.collect::<HashSet<_>>()
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.difference(&keydeps)
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.into_iter()
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.map(|k| k.to_owned().to_owned())
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.collect()
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}
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fn find(map: &HashMap<Position2D, char>, c: char) -> Option<Position2D> {
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map.keys().find(|p| map.get(&p) == Some(&c)).copied()
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}
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fn clear_field(map: &mut HashMap<Position2D, char>, p: &Position2D) {
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map.insert(*p, '.');
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}
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fn remove(map: &mut HashMap<Position2D, char>, k: Key) {
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let key_pos = find(map, k.0).unwrap();
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clear_field(map, &key_pos);
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if let Some(door_pos) = find(map, k.0.to_uppercase().next().unwrap()) {
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clear_field(map, &door_pos);
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}
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}
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/*
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fn distance_to_door(map: &HashMap<Position2D, char>, k: &Key) -> usize {
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let (distances, _, _) = traverse(map, find(map, k.0).unwrap());
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let door_pos = find(map, k.0.to_uppercase().next().unwrap());
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*door_pos.map(|p| distances.get(&p).unwrap()).unwrap_or(&10)
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}
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fn distance_to_locked_door(map: &HashMap<Position2D, char>, k: &Key) -> usize {
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let (distances, _, doors) = traverse(map, find(map, k.0).unwrap());
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*doors
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.keys()
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.map(|d| find(map, d.0).unwrap())
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.map(|p| distances.get(&p).unwrap_or(&9999999999999))
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.min()
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.unwrap_or(&0)
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}
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*/
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fn next_key(
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map: &mut HashMap<Position2D, char>,
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pos: &Position2D,
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steps: usize,
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) -> usize {
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if too_slow(steps) {
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// println!("Aborting after {} steps", steps);
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return 999999;
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}
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let (distances, dependencies, door_dependencies) = traverse(map, pos.to_owned());
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//dbg!(distances.get(&find('c').unwrap()));
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if dependencies.len() == 0 {
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// println!("End of path after {} steps", steps);
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replace(steps);
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return steps;
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}
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let reachable_doors: HashSet<_> = door_dependencies
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.iter()
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.filter_map(|(door, doors)| if doors.is_empty() { Some(door) } else { None })
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.collect();
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let mut useful_keys: Vec<_> = dependencies
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.iter()
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.filter(|(_, (_, d))| d.is_empty())
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.filter(|(k, _)| {
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reachable_doors.contains(&Door {
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0: k.0.to_uppercase().next().unwrap(),
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})
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})
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//.min_by_key(|(k, _)| distances.get(&find(k.0).unwrap()))
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//.unwrap()
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.map(|(k, _)| {
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(
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k,
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distances
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.get(&find(map, k.0).expect("could not find key"))
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.expect("No distance to key")
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.mul(1),
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)
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})
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.collect();
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//.min_by_key(|k| )
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let nearest = dependencies.iter()
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.filter(|(_, (_, d))| d.is_empty())
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.min_by_key(|(k, _)| distances.get(&find(&map, k.0).unwrap()));
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let dead_end_keys = find_keys_at_dead_ends(&dependencies);
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let mut next: Vec<_> = dead_end_keys
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.iter()
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.filter(|k| dependencies.get(k).expect("not in deps").1.is_empty())
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.map(|k| {
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(
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k,
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distances
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.get(&find(map, k.0).expect("could not find key #2"))
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.expect("No distance to key #2")
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.mul(1),
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)
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})
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//.min_by_key(|k| distances.get(&find(k.0).unwrap()))
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//.chain(useful_keys)
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.collect();
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next.sort_by_key(|(k, n)| *n);//*3 + distance_to_door(map, k));
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nearest.map(|(k, _)| next.insert(0, (k, *distances.get(&find(map, k.0).unwrap()).expect("No distance to nearest?"))));
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useful_keys.sort_by_key(|(k, n)| *n);
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useful_keys.reverse();
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useful_keys.pop().map(|k| next.insert(0, k));
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//useful_keys.pop().map(|k| next.push(k));
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useful_keys.pop().map(|k| next.push(k));
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useful_keys.pop().map(|k| next.push(k));
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let len = next.len();
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next.par_iter()
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.take((len.min(4) - 1).max(1))
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.map(|(k, _)| {
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let mut map2 = map.clone();
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let next_pos = find(&map2, k.0).expect("Could not find key #3");
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let steps_after_next = steps + distances.get(&next_pos).expect("No distance to key #3");
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// collect keys on the way (if any)
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for k in &dependencies.get(&k).expect("No dependency found").0 {
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remove(&mut map2, k.to_owned());
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}
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remove(&mut map2, k.to_owned().to_owned());
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next_key(&mut map2, &next_pos, steps_after_next)
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})
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.min()
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.unwrap()
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}
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fn main() {
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let map: HashMap<Position2D, char> = io::stdin()
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.lock()
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.lines()
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.enumerate()
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.flat_map(move |(y, l)| {
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l.unwrap()
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.to_owned()
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.chars()
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.enumerate()
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.map(move |(x, c)| ((x, y).into(), c))
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.collect::<Vec<_>>()
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})
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.collect();
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let pos = find(&map, '@').unwrap();
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//let steps = 0;
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//let (_, dependencies, _) = traverse(&map, pos.to_owned());
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let p1 = next_key(&mut map.clone(), &pos, 0);
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println!("Part 1: {}", p1);
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println!("Part 1: {}", BEST.lock().unwrap());
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}
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