day23: problem 1 solution
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236
23/src/main.rs
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236
23/src/main.rs
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@ -0,0 +1,236 @@
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use itertools::Itertools;
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use ndarray::prelude::*;
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use petgraph::algo::all_simple_paths;
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use petgraph::prelude::*;
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use std::collections::HashMap;
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use std::fmt::{Debug, Display, Write};
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use std::fs::File;
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use std::io::{BufRead, BufReader, Lines};
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use std::time::Instant;
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// BOILERPLATE
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type InputIter = Lines<BufReader<File>>;
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fn get_input() -> InputIter {
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let f = File::open("input").unwrap();
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let br = BufReader::new(f);
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br.lines()
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}
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fn main() {
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let start = Instant::now();
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let ans1 = problem1(get_input());
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let duration = start.elapsed();
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println!("Problem 1 solution: {} [{}s]", ans1, duration.as_secs_f64());
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let start = Instant::now();
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let ans2 = problem2(get_input());
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let duration = start.elapsed();
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println!("Problem 2 solution: {} [{}s]", ans2, duration.as_secs_f64());
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}
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// PARSE
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#[derive(Debug, Clone)]
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enum EdgeType {
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FromPath,
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FromSlope,
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}
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#[derive(Debug, Clone)]
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struct Node {
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c: char,
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pos: Position,
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}
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type Position = (usize, usize);
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#[derive(Clone)]
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struct ForestMap {
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map: Array2<char>,
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indexes: HashMap<Position, NodeIndex>,
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graph: DiGraph<Node, EdgeType>,
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start: Position,
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end: Position,
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}
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const ADJACENCIES: [(isize, isize); 4] = [(-1, 0), (1, 0), (0, -1), (0, 1)];
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fn offset_pos(map: &Array2<char>, pos: Position, ofs: (isize, isize)) -> Option<Position> {
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let new_pos = (pos.0 as isize + ofs.0, pos.1 as isize + ofs.1);
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if new_pos.0 >= 0
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&& new_pos.0 < map.len_of(Axis(0)) as isize
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&& new_pos.1 >= 0
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&& new_pos.1 < map.len_of(Axis(1)) as isize
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{
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Some((new_pos.0 as usize, new_pos.1 as usize))
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} else {
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None
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}
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}
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fn adjacent_to(map: &Array2<char>, pos: Position) -> Vec<Position> {
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ADJACENCIES
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.iter()
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.filter_map(|ofs| offset_pos(map, pos, *ofs))
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.collect()
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}
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impl<T: BufRead> From<Lines<T>> for ForestMap {
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fn from(lines: Lines<T>) -> Self {
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let rows = lines.map(|line| line.unwrap().chars().collect_vec()).collect_vec();
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let map = Array::from_shape_vec([rows[0].len(), rows.len()], rows.into_iter().flatten().collect_vec())
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.unwrap()
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.reversed_axes();
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let start = (map.slice(s![.., 0]).iter().position(|c| *c == '.').unwrap(), 0);
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let end = (
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map.slice(s![.., map.len_of(Axis(1)) - 1])
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.iter()
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.position(|c| *c == '.')
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.unwrap(),
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map.len_of(Axis(1)) - 1,
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);
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let mut graph = Graph::default();
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let mut indexes = HashMap::new();
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for (pos, c) in map.indexed_iter() {
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if *c != '#' {
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indexes.insert(pos, graph.add_node(Node { c: *c, pos }));
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}
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}
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for (pos, c) in map.indexed_iter() {
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match c {
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'#' => continue,
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'.' => {
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adjacent_to(&map, pos).iter().for_each(|adj| {
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if indexes.contains_key(&adj) {
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graph.add_edge(indexes[&pos], indexes[adj], EdgeType::FromPath);
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}
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});
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}
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'^' => {
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if let Some(adj) = offset_pos(&map, pos, (0, -1)) {
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if indexes.contains_key(&adj) {
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graph.add_edge(indexes[&pos], indexes[&adj], EdgeType::FromSlope);
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}
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}
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}
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'>' => {
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if let Some(adj) = offset_pos(&map, pos, (1, 0)) {
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if indexes.contains_key(&adj) {
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graph.add_edge(indexes[&pos], indexes[&adj], EdgeType::FromSlope);
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}
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}
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}
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'v' => {
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if let Some(adj) = offset_pos(&map, pos, (0, 1)) {
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if indexes.contains_key(&adj) {
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graph.add_edge(indexes[&pos], indexes[&adj], EdgeType::FromSlope);
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}
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}
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}
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'<' => {
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if let Some(adj) = offset_pos(&map, pos, (-1, 0)) {
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if indexes.contains_key(&adj) {
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graph.add_edge(indexes[&pos], indexes[&adj], EdgeType::FromSlope);
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}
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}
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}
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c => panic!("invalid map character {}", c),
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}
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}
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Self {
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map,
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start,
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end,
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graph,
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indexes,
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}
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}
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}
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impl Debug for ForestMap {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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for y in 0..self.map.len_of(Axis(1)) {
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for c in self.map.index_axis(Axis(1), y) {
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f.write_char(*c)?;
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}
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writeln!(f)?;
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}
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// println!("start: {:?} end: {:?}", self.start, self.end);
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// println!("digraph aoc23 {{");
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// for node in self.graph.node_indices() {
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// println!(
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// " \"{},{}\" -> {}",
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// self.graph[node].pos.0,
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// self.graph[node].pos.1,
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// self.graph
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// .neighbors(node)
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// .map(|n| format!("\"{},{}\"", self.graph[n].pos.0, self.graph[n].pos.1))
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// .join(",")
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// );
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// }
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// println!("}}");
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Ok(())
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}
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}
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// PROBLEM 1 solution
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fn problem1<T: BufRead>(input: Lines<T>) -> u64 {
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let map = ForestMap::from(input);
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println!("{:?}", map);
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let paths = all_simple_paths::<Vec<_>, _>(&map.graph, map.indexes[&map.start], map.indexes[&map.end], 0, None)
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.collect_vec();
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let longest = paths.iter().max_by_key(|path| path.len()).unwrap();
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longest.len() as u64 - 1
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}
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// PROBLEM 2 solution
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fn problem2<T: BufRead>(input: Lines<T>) -> u64 {
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0
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}
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#[cfg(test)]
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mod tests {
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use crate::*;
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use std::io::Cursor;
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const EXAMPLE: &str = &"#.#####################
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#.......#########...###
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#######.#########.#.###
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###.....#.>.>.###.#.###
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###v#####.#v#.###.#.###
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###.>...#.#.#.....#...#
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###v###.#.#.#########.#
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###...#.#.#.......#...#
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#####.#.#.#######.#.###
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#.....#.#.#.......#...#
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#.#####.#.#.#########v#
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#.#...#...#...###...>.#
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#.#.#v#######v###.###v#
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#...#.>.#...>.>.#.###.#
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#####v#.#.###v#.#.###.#
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#.....#...#...#.#.#...#
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#.#########.###.#.#.###
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#...###...#...#...#.###
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###.###.#.###v#####v###
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#...#...#.#.>.>.#.>.###
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#.###.###.#.###.#.#v###
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#.....###...###...#...#
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#####################.#";
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#[test]
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fn problem1_example() {
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let c = Cursor::new(EXAMPLE);
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assert_eq!(problem1(c.lines()), 94);
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}
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#[test]
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fn problem2_example() {
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let c = Cursor::new(EXAMPLE);
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assert_eq!(problem2(c.lines()), 0);
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}
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}
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