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nora 2024-12-04 22:23:04 +01:00
parent f55e51c955
commit 5627d5ac60
1 changed files with 24 additions and 28 deletions
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52
2024/day04/src/lib.rs
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@ -477,25 +477,25 @@ fn part2_reading(input: &str) -> u64 {
#[rustfmt::skip]
const XMAS_COMBINATIONS: &[(u64, u8)] = &[
(u64::from_le_bytes([
b'M', 0, b'S',
b'S', 0, b'M',
0, b'A', 0,
b'M', 0,
]), b'S'),
(u64::from_le_bytes([
b'M', 0, b'M',
0, b'A', 0,
b'S', 0,
]), b'S'),
b'S', 0
]), b'M'),
(u64::from_le_bytes([
b'S', 0, b'S',
0, b'A', 0,
b'M', 0
]), b'M'),
(u64::from_le_bytes([
b'S', 0, b'M',
b'M', 0, b'M',
0, b'A', 0,
b'S', 0
]), b'M'),
b'S', 0,
]), b'S'),
(u64::from_le_bytes([
b'M', 0, b'S',
0, b'A', 0,
b'M', 0,
]), b'S'),
];
let all = input.as_bytes();
@ -531,28 +531,24 @@ fn part2_reading(input: &str) -> u64 {
.cast::<u32>()
.read_unaligned() as u64;
let int = (chunk_top & 0xFFFFFF)
| ((chunk_mid & 0xFFFFFF) << 24)
| ((chunk_bot & 0xFFFFFF) << 24 * 2);
let int = (chunk_top & 0xFF00FF)
| ((chunk_mid & 0x00FF00) << 24)
| ((chunk_bot & 0xFF00FF) << (24 * 2));
let to_test = x86_64::_mm256_set1_epi64x(
(int & 0xFF00FF_00FF00_FF00_u64.swap_bytes()) as i64,
);
let to_test = x86_64::_mm256_set1_epi64x(int as i64);
let eq = x86_64::_mm256_cmpeq_epi64(to_test, combinations);
let movmask = x86_64::_mm256_movemask_epi8(eq);
let movmask = x86_64::_mm256_movemask_epi8(eq) as u32;
if movmask != 0 {
let check = match movmask as u32 {
0xFF000000 => XMAS_COMBINATIONS[0].1,
0x00FF0000 => XMAS_COMBINATIONS[1].1,
0x0000FF00 => XMAS_COMBINATIONS[2].1,
0x000000FF => XMAS_COMBINATIONS[3].1,
_ => unreachable!(),
};
if check == ((chunk_bot >> 16) & 0xFF) as u8 {
count += 1;
}
let masked_selected = u32::from_be_bytes([
XMAS_COMBINATIONS[0].1,
XMAS_COMBINATIONS[1].1,
XMAS_COMBINATIONS[2].1,
XMAS_COMBINATIONS[3].1,
]) & movmask;
let check = masked_selected >> masked_selected.trailing_zeros();
count += (check as u8 == ((chunk_bot >> 16) & 0xFF) as u8) as u64;
}
i += 1;