104 lines
2.6 KiB
Rust
104 lines
2.6 KiB
Rust
#![feature(test)]
|
|
extern crate test;
|
|
use std::mem::transmute;
|
|
|
|
use aoc2023::{
|
|
boilerplate,
|
|
common::*,
|
|
direction::{Direction, ALL_DIRECTIONS},
|
|
position::{Position2D, PositionND},
|
|
};
|
|
use itertools::Itertools;
|
|
|
|
const DAY: usize = 10;
|
|
|
|
#[allow(dead_code)]
|
|
#[derive(Debug, Copy, Clone, PartialEq)]
|
|
#[repr(u8)]
|
|
enum Pipe {
|
|
Vertical = b'|',
|
|
Horizontal = b'-',
|
|
TopRight = b'L',
|
|
TopLeft = b'J',
|
|
BottomRight = b'F',
|
|
BottomLeft = b'7',
|
|
None = b'.',
|
|
Start = b'S',
|
|
}
|
|
|
|
impl Pipe {
|
|
fn openings(self) -> [Direction; 2] {
|
|
match self {
|
|
Pipe::Vertical => [Direction::Up, Direction::Down],
|
|
Pipe::Horizontal => [Direction::Left, Direction::Right],
|
|
Pipe::TopRight => [Direction::Up, Direction::Right],
|
|
Pipe::TopLeft => [Direction::Up, Direction::Left],
|
|
Pipe::BottomRight => [Direction::Down, Direction::Right],
|
|
Pipe::BottomLeft => [Direction::Down, Direction::Left],
|
|
Pipe::None | Pipe::Start => unimplemented!(),
|
|
}
|
|
}
|
|
}
|
|
|
|
type Parsed<'a> = (Pos, Vec<&'a [Pipe]>);
|
|
type Pos = Position2D<usize>;
|
|
|
|
fn parse_input(raw: &str) -> Parsed {
|
|
let grid = raw.lines().rev().map(|l| unsafe { transmute::<&str, &[Pipe]>(l) }).collect_vec();
|
|
let start = grid
|
|
.iter()
|
|
.enumerate()
|
|
.find_map(|(y, line)| line.iter().enumerate().find_map(|(x, p)| (*p == Pipe::Start).then_some(PositionND([x, y]))))
|
|
.unwrap();
|
|
(start, grid)
|
|
}
|
|
|
|
fn step(PositionND([x, y]): Pos, dir: Direction) -> Pos {
|
|
match dir {
|
|
Direction::Up => PositionND([x, y + 1]),
|
|
Direction::Right => PositionND([x + 1, y]),
|
|
Direction::Left => PositionND([x - 1, y]),
|
|
Direction::Down => PositionND([x, y - 1]),
|
|
}
|
|
}
|
|
|
|
fn part1((start, grid): &Parsed) -> usize {
|
|
ALL_DIRECTIONS
|
|
.iter()
|
|
.cloned()
|
|
.map(|mut dir| {
|
|
let mut pos = *start;
|
|
let mut steps = 0;
|
|
loop {
|
|
steps += 1;
|
|
pos = step(pos, dir);
|
|
if &pos == start {
|
|
return steps / 2;
|
|
}
|
|
dir = *grid[pos.0[1]][pos.0[0]].openings().iter().find(|&&o| o != !dir).unwrap();
|
|
}
|
|
})
|
|
.max()
|
|
.unwrap()
|
|
}
|
|
|
|
fn part2(parsed: &Parsed) -> usize {
|
|
unimplemented!()
|
|
}
|
|
|
|
boilerplate! {
|
|
TEST_INPUT == "\
|
|
-L|F7
|
|
7S-7|
|
|
L|7||
|
|
-L-J|
|
|
L|-JF",
|
|
tests: {
|
|
part1: { TEST_INPUT => 4 },
|
|
part2: { TEST_INPUT => 0 },
|
|
},
|
|
bench1 == 6923,
|
|
bench2 == 0,
|
|
bench_parse: |p: &Parsed| (p.0, p.1.len()) => (PositionND([114, 117]), 140),
|
|
}
|