bendns' repos / aoc
heh
Diffstat (limited to 'src/main.rs')
-rw-r--r--src/main.rs99
1 files changed, 48 insertions, 51 deletions
diff --git a/src/main.rs b/src/main.rs
index 215ee46..c8a48f6 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -23,63 +23,60 @@
)]
extern crate test;
pub mod util;
+use std::{io::BufRead, mem::MaybeUninit};
+
pub use util::prelude::*;
-pub fn iterg<I: Iterator<Item = (u8, u8, u16)>>(
- start: (u8, u8, u16, Box<[u64; 312]>),
- graph: &mut impl Fn((u8, u8, u16)) -> I,
- end: &mut impl Fn((u8, u8)) -> bool,
- finally: &mut impl FnMut(u16),
-) {
- if end((start.0, start.1)) {
- finally(start.2);
- } else {
- graph((start.0, start.1, start.2))
- .map(|(a, b, n)| {
- let shift = (a.nat() * 141 + b.nat()) % 64;
- let index = (a.nat() * 141 + b.nat()) / 64;
- if start.3[index] & (1 << shift) == 0 {
- let mut m = start.3.clone();
- m[index] |= 1 << shift;
- iterg((a, b, n, m), graph, end, finally)
- }
- })
- .Θ();
- };
+pub fn intersect(
+ p0x: f64,
+ p0y: f64,
+ v0x: f64,
+ v0y: f64,
+ p1x: f64,
+ p1y: f64,
+ v1x: f64,
+ v1y: f64,
+) -> Option<(f64, f64)> {
+ let x = ((p1y - p0y) + p0x * (v0y / v0x) - p1x * (v1y / v1x)) / ((v0y / v0x) - (v1y / v1x));
+ let t0 = (x - p0x) / v0x;
+ let t1 = (x - p1x) / v1x;
+ (t0 > 0. && t1 > 0.).then_some((x, p0y + t0 * v0y))
}
pub fn run(i: &str) -> impl Display {
- let x = i.行().collect_vec();
- let i = x.as_slice();
- let end = (x.len() as u8 - 2, x.len() as u8 - 1);
+ let mut v: [MaybeUninit::<_>; 300] =
+ // SAFETY: mu likes this
+ unsafe { MaybeUninit::uninit().assume_init() };
+ let mut x = i.as_bytes();
+ for i in 0..300 {
+ let α = 読む::迄::<i64>(&mut x, b',') as f64;
+ x.skip(1);
+ let β = 読む::迄::<i64>(&mut x, b',') as f64;
+ x.skip(2);
+ while x.by().ψ() != b' ' {}
+ x.skip(2);
+ let δ = 読む::負迄(&mut x, b',') as f64;
+ x.skip(1);
+ let ε = 読む::負迄(&mut x, b',') as f64;
+ x.skip(1);
+ if let Some(n) = memchr::memchr(b'\n', x) {
+ x.skip(n + 1);
+ }
+ v[i].write(([α, β], [δ, ε]));
+ }
+ let v = v.map(|elem| unsafe { elem.assume_init() });
let mut sum = 0;
- iterg(
- (1u8, 0u8, 0u16, Box::new([0; 312])),
- &mut |(x, y, n)| {
- let v = match i[y.nat()][x.nat()] {
- b'>' => vec![(x + 1, y, n + 1)],
- b'<' => vec![(x - 1, y, n + 1)],
- b'^' => vec![(x, y - 1, n + 1)],
- b'v' => vec![(x, y + 1, n + 1)],
- _ => [
- Dir::N + (x, y),
- Dir::E + (x, y),
- Dir::S + (x, y),
- Dir::W + (x, y),
- ]
- .into_iter()
- .flatten()
- .fl(lt(141))
- .fr(lt(141))
- .filter(|(x, y)| i[y.nat()][x.nat()] != b'#')
- .map(|(x, y)| (x, y, n + 1))
- .collect_vec(),
- };
- v.into_iter()
- },
- &mut |(x, y)| (x, y) == end,
- &mut |x| sum = sum.max(x),
- );
+ for (i, &([x0, y0], [v0x, v0y])) in v.iter().enumerate() {
+ for &([x1, y1], [v1x, v1y]) in &v[i..] {
+ if let Some((x, y)) = intersect(x0, y0, v0x, v0y, x1, y1, v1x, v1y) {
+ let min = 200000000000000.;
+ let max = 400000000000000.;
+ if x > min && x < max && y > min && y < max {
+ sum += 1;
+ }
+ }
+ }
+ }
sum
}