bendns' repos / aoc
heh
Diffstat (limited to 'src/main.rs')
-rw-r--r--src/main.rs93
1 files changed, 49 insertions, 44 deletions
diff --git a/src/main.rs b/src/main.rs
index 22e07cc..2d8ed86 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -18,54 +18,59 @@ extern crate test;
pub mod util;
pub use util::prelude::*;
-// const MUST: i16 = 3;
-// const NEEDS: i16 = 0;
-const MUST: i16 = 10;
-const NEEDS: i16 = 4;
+// const MUST: u8 = 3;
+// const NEEDS: u8 = 0;
+const MUST: u8 = 10;
+const NEEDS: u8 = 4;
-pub fn run(i: &str) -> impl Display {
- let v = i.行().collect_vec();
- let g = util::LMap::new(|(x, y, δx, δy, gone): (i16, i16, i16, i16, i16)| {
- Some(
- [
- Dir::W + (x, y),
- Dir::E + (x, y),
- Dir::N + (x, y),
- Dir::S + (x, y),
- ]
- .iter()
- .filter_map(|&(nx, ny)| {
- let ngon;
- let nδx = nx - x;
- let nδy = ny - y;
- if nδx == δx && nδy == δy {
- if gone == MUST {
- return None;
- }
- ngon = gone + 1;
- } else if (nδx == -δx && nδx != 0) || (nδy == -δy && nδy != 0) {
- return None;
- } else {
- if gone < NEEDS {
- return None;
- }
- ngon = 1;
- }
- (nx >= 0 && nx < v[0].len() as i16 && ny >= 0 && ny < v.len() as i16).then(|| {
- (
- (nx, ny, nδx, nδy, ngon),
- (v[ny as usize][nx as usize] - b'0') as u32,
- )
- })
- })
- .collect_vec(),
- )
- });
- util::dijkstra(g, (0i16, 0i16, 0i16, 0i16, NEEDS), |(x, y, _, _, g)| {
- x == v[0].len() as i16 - 1 && y == v.len() as i16 - 1 && g >= NEEDS
+fn neighbor(
+ (x, y, δx, δy, gone): (u8, u8, i8, i8, u8),
+ v: &[[u8; 142]; 141],
+) -> impl Iterator<Item = ((u8, u8, i8, i8, u8), u16)> + '_ {
+ [
+ Dir::W + (x, y),
+ Dir::E + (x, y),
+ Dir::N + (x, y),
+ Dir::S + (x, y),
+ ]
+ .into_iter()
+ .flatten()
+ .filter(|&(x, _)| x < 141)
+ .filter(|&(_, y)| y < 141)
+ .filter_map(move |(nx, ny)| {
+ let go;
+ let nδx = (nx as i16 - x as i16) as i8;
+ let nδy = (ny as i16 - y as i16) as i8;
+ if nδx == δx && nδy == δy {
+ if gone == MUST {
+ return None;
+ }
+ go = gone + 1;
+ } else if (nδx == -δx && nδx != 0) || (nδy == -δy && nδy != 0) {
+ return None;
+ } else {
+ if gone < NEEDS {
+ return None;
+ }
+ go = 1;
+ }
+
+ Some((
+ (nx, ny, nδx, nδy, go),
+ (C! { v[ny as usize][nx as usize] } - b'0') as u16,
+ ))
})
}
+pub fn run(i: &str) -> impl Display {
+ let v = unsafe { &*(i.as_bytes().as_ptr() as *const [[u8; 142]; 141]) };
+ util::dijkstra(
+ |n| neighbor(n, v),
+ (0u8, 0u8, 0i8, 0i8, NEEDS),
+ |(x, y, _, _, g)| x == 140 && y == 140 && g >= NEEDS,
+ )
+}
+
fn main() {
let i = include_str!("inp.txt").trim();
println!("{}", run(i));