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use rpds::rbt_set;
use rpds::vector;
use rpds::vector::Vector;
use rpds::RedBlackTreeMap;
use rpds::RedBlackTreeSet;
use std::io;
use std::io::prelude::*;
use std::iter;
use std::iter::FromIterator;
use std::process;
use structopt::StructOpt;
#[derive(Debug, StructOpt)]
#[structopt(name = "Day 20: Donut Maze")]
/// Finds the shortest path through a maze with portals.
///
/// See https://adventofcode.com/2019/day/20 for details.
struct Opt {}
fn main() {
let stdin = io::stdin();
let _opt = Opt::from_args();
let maze = stdin
.lock()
.lines()
.map(|x| exit_on_failed_assertion(x, "Error reading input"))
.collect::<MazeBuilder>()
.build();
println!("{}", maze.shortest_route());
}
fn exit_on_failed_assertion<A, E: std::error::Error>(data: Result<A, E>, message: &str) -> A {
match data {
Ok(data) => data,
Err(e) => {
eprintln!("{}: {}", message, e);
process::exit(1);
}
}
}
struct MazeBuilder {
map: Vector<Vector<char>>,
portals: Vector<([char; 2], Point)>,
}
impl FromIterator<String> for MazeBuilder {
fn from_iter<T: IntoIterator<Item = String>>(iter: T) -> Self {
MazeBuilder {
map: iter
.into_iter()
.map(|line| line.chars().collect())
.collect(),
portals: Vector::new(),
}
}
}
impl MazeBuilder {
fn build(self) -> Maze {
Maze {
walls: self
.map
.iter()
.map(|line| line.iter().map(|ch| *ch != '.').collect())
.collect(),
portals: self.grouped_portals(),
entrance: self
.all_portals()
.find(|(id, _)| *id == ['A', 'A'])
.unwrap()
.1,
exit: self
.all_portals()
.find(|(id, _)| *id == ['Z', 'Z'])
.unwrap()
.1,
}
}
fn grouped_portals(&self) -> Vector<(Point, Point)> {
self.all_portals()
.fold(
(Vector::new(), RedBlackTreeMap::new()),
|(matched, unmatched): (
Vector<(Point, Point)>,
RedBlackTreeMap<[char; 2], Point>,
),
(next_id, next_p)| match unmatched.get(&next_id) {
Some(pair) => (
matched.push_back((pair.clone(), next_p)),
unmatched.remove(&next_id),
),
None => (matched, unmatched.insert(next_id, next_p)),
},
)
.0
}
fn all_portals(&self) -> impl Iterator<Item = ([char; 2], Point)> + '_ {
self.horizontal_trailing_portals()
.chain(self.horizontal_leading_portals())
.chain(self.vertical_trailing_portals())
.chain(self.vertical_leading_portals())
}
fn horizontal_trailing_portals(&self) -> impl Iterator<Item = ([char; 2], Point)> + '_ {
// .XX
(0..self.map.len())
.flat_map(move |y| (0..self.map[y].len() - 2).map(move |x| Point { x, y }))
.filter(move |p| {
self.map[p.y][p.x] == '.'
&& self.map[p.y][p.x + 1].is_alphabetic()
&& self.map[p.y][p.x + 2].is_alphabetic()
})
.map(move |p| ([self.map[p.y][p.x + 1], self.map[p.y][p.x + 2]], p))
}
fn horizontal_leading_portals(&self) -> impl Iterator<Item = ([char; 2], Point)> + '_ {
// XX.
(0..self.map.len())
.flat_map(move |y| (0..self.map[y].len() - 2).map(move |x| Point { x, y }))
.filter(move |p| {
self.map[p.y][p.x + 2] == '.'
&& self.map[p.y][p.x + 1].is_alphabetic()
&& self.map[p.y][p.x].is_alphabetic()
})
.map(move |p| {
(
[self.map[p.y][p.x], self.map[p.y][p.x + 1]],
Point { x: p.x + 2, y: p.y },
)
})
}
fn vertical_trailing_portals(&self) -> impl Iterator<Item = ([char; 2], Point)> + '_ {
// .XX
(0..self.map[0].len())
.flat_map(move |x| (0..self.map.len() - 2).map(move |y| Point { x, y }))
.filter(move |p| {
self.map[p.y][p.x] == '.'
&& self.map[p.y + 1][p.x].is_alphabetic()
&& self.map[p.y + 2][p.x].is_alphabetic()
})
.map(move |p| ([self.map[p.y + 1][p.x], self.map[p.y + 2][p.x]], p))
}
fn vertical_leading_portals(&self) -> impl Iterator<Item = ([char; 2], Point)> + '_ {
// XX.
(0..self.map[0].len())
.flat_map(move |x| (0..self.map.len() - 2).map(move |y| Point { x, y }))
.filter(move |p| {
self.map[p.y + 2][p.x] == '.'
&& self.map[p.y + 1][p.x].is_alphabetic()
&& self.map[p.y][p.x].is_alphabetic()
})
.map(move |p| {
(
[self.map[p.y][p.x], self.map[p.y + 1][p.x]],
Point { x: p.x, y: p.y + 2 },
)
})
}
}
#[derive(Debug)]
struct Maze {
walls: Vector<Vector<bool>>,
portals: Vector<(Point, Point)>,
entrance: Point, // AA
exit: Point, // ZZ
}
#[derive(Debug, Clone)]
struct Point {
x: usize,
y: usize,
}
impl Maze {
fn shortest_route(&self) -> usize {
unimplemented!()
}
}
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