bendns' repos / aoc
heh
less memchr calls
Browse Source
bendn 2024-12-07
parent 201c0d9 · commit a726b3a
Diffstat
-rw-r--r--src/main.rs33
1 files changed, 17 insertions, 16 deletions
diff --git a/src/main.rs b/src/main.rs
index 4e43ba2..246cbd5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -75,21 +75,22 @@ impl bitset17030 {
// }
// }
-fn follow(i: &[u8]) -> bitset17030 {
+fn follow(i: &[u8]) -> (i64, bitset17030) {
let mut marked = bitset17030::new();
let mut position = memchr::memchr(b'^', i).ψ() as i64;
+ let guard = position;
let mut pointing = 0u8;
- loop {
+ 'outer: loop {
match pointing {
0 => loop {
marked.set(position as usize);
let check = position - SIZE as i64 - 1;
if check < 0 {
- return marked;
+ break 'outer;
}
match C! { i[check as usize] } {
- b'\n' => return marked,
+ b'\n' => break 'outer,
b'#' => break,
_ => position = check,
};
@@ -98,7 +99,7 @@ fn follow(i: &[u8]) -> bitset17030 {
marked.set(position as usize);
let check = position + 1;
match C! { i[check as usize] } {
- b'\n' => return marked,
+ b'\n' => break 'outer,
b'#' => break,
_ => position = check,
};
@@ -107,7 +108,7 @@ fn follow(i: &[u8]) -> bitset17030 {
marked.set(position as usize);
let check = position + SIZE as i64 + 1;
match C! { i[check as usize] } {
- b'\n' => return marked,
+ b'\n' => break 'outer,
b'#' => break,
_ => position = check,
};
@@ -116,10 +117,10 @@ fn follow(i: &[u8]) -> bitset17030 {
marked.set(position as usize);
let check = position - 1;
if check < 0 {
- return marked;
+ break 'outer;
}
match C! { i[check as usize] } {
- b'\n' => return marked,
+ b'\n' => break 'outer,
b'#' => break,
_ => position = check,
};
@@ -129,19 +130,20 @@ fn follow(i: &[u8]) -> bitset17030 {
pointing += 1;
pointing %= 4;
}
+ (guard, marked)
}
#[no_mangle]
pub fn run(i: &str) -> impl Display {
- follow(i.as_bytes()).popcnt()
+ follow(i.as_bytes()).1.popcnt()
}
#[no_mangle]
pub fn p2(i: &str) -> impl Display {
let i = i.as_bytes();
- fn run(i: &[u8], obstacle: i64) -> bool {
+ fn run(i: &[u8], guard: i64, obstacle: i64) -> bool {
let mut marked = [bitset17030::new(); 4];
- let mut position = memchr::memchr(b'^', i).ψ() as i64;
+ let mut position = guard;
let mut pointing = 0u8;
macro_rules! check {
@@ -199,14 +201,13 @@ pub fn p2(i: &str) -> impl Display {
pointing %= 4;
}
}
- let marked = follow(&i);
+ let (guard, marked) = follow(&i);
use rayon::prelude::*;
- (0..SIZE)
- .flat_map(|x| (0..SIZE).map(move |y| (y * (SIZE + 1) + x)))
+ (0..SIZE * (SIZE + 1))
.filter(|&i| marked.get(i))
- .filter(|&j| i[j] == b'.')
+ .filter(|&j| C! { i[j] } == b'.')
.par_bridge()
- .filter(|&j| run(&i, j as i64))
+ .filter(|&j| run(&i, guard, j as i64))
.count()
}