60 lines
1.6 KiB
Rust
60 lines
1.6 KiB
Rust
#![warn(clippy::pedantic)]
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use std::{
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collections::{HashMap, HashSet},
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io::{stdin, BufRead},
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};
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type Point<'a> = &'a str;
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fn walk<'a>(
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connections: &HashMap<Point<'a>, HashSet<Point<'a>>>,
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visited: &[Point<'a>],
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extra_cave: Option<Point<'a>>,
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from: Point<'a>,
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) -> usize {
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let mut res = 0;
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let mut visited = Vec::from(visited);
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visited.push(from);
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for target in &connections[from] {
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if *target == "end" {
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res += 1;
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continue;
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}
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let is_uppercase = target.chars().all(|c| c.is_ascii_uppercase());
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let was_visited = visited.contains(target);
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if is_uppercase || !was_visited {
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res += walk(connections, &visited, extra_cave, target);
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} else if extra_cave.is_none() {
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res += walk(connections, &visited, Some(target), target);
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}
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}
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res
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}
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fn main() {
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let lines: Vec<_> = stdin().lock().lines().collect::<Result<_, _>>().unwrap();
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let connections: HashMap<Point, HashSet<Point>> =
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lines.iter().fold(HashMap::new(), |mut map, line| {
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let mut parts = line.split('-');
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let p1 = parts.next().unwrap();
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let p2 = parts.next().unwrap();
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if p1 != "end" && p2 != "start" {
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map.entry(p1).or_default().insert(p2);
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}
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if p2 != "end" && p1 != "start" {
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map.entry(p2).or_default().insert(p1);
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}
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map
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});
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println!("{}", walk(&connections, &[], Some(""), "start"));
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println!("{}", walk(&connections, &[], None, "start"));
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}
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