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day8: optimized

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This commit is contained in:
Ishan Jain 2023-12-08 15:16:32 +05:30
parent 10a38b6f3b
commit dc2b3c56e9
Signed by: ishan
GPG Key ID: 0506DB2A1CC75C27
2 changed files with 62 additions and 23 deletions
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35
src/day8/1.rs
View File

@ -1,8 +1,6 @@
#![feature(slice_split_once)]
#![feature(test)]
use std::collections::HashMap;
extern crate test;
const INPUTS: [&[u8]; 2] = [
@ -29,8 +27,7 @@ const INPUTS: [&[u8]; 2] = [
fn process(data: &[u8]) -> usize {
let (seq, remain) = data.split_once(|&x| x == b'\n').unwrap();
let mut map = HashMap::new();
let mut map = vec![];
for line in remain.split(|&x| x == b'\n').skip(1) {
if line.is_empty() {
continue;
@ -38,17 +35,29 @@ fn process(data: &[u8]) -> usize {
let (start, remain) = line.split_at(3);
let (l, r) = (&remain[4..7], &remain[9..12]);
map.insert(start, (l, r));
// Pack data into 6 bytes each
let start = lut(start[0]) << 10 | lut(start[1]) << 5 | lut(start[2]);
let l = lut(l[0]) << 10 | lut(l[1]) << 5 | lut(l[2]);
let r = lut(r[0]) << 10 | lut(r[1]) << 5 | lut(r[2]);
if start >= map.len() {
map.extend(std::iter::repeat(None).take(start - map.len() + 1));
}
let mut pos: &[u8] = &[b'A', b'A', b'A'];
map[start] = Some((l, r));
}
const AAA: usize = lut(b'A') << 10 | lut(b'A') << 5 | lut(b'A');
const ZZZ: usize = lut(b'Z') << 10 | lut(b'Z') << 5 | lut(b'Z');
let mut pos = AAA;
for (i, ins) in seq.iter().cycle().enumerate() {
if pos == [b'Z', b'Z', b'Z'] {
if pos == ZZZ {
return i;
}
let (l, r) = map.get(&pos).unwrap();
let (l, r) = map[pos].unwrap();
match ins {
b'L' => pos = l,
@ -61,6 +70,16 @@ fn process(data: &[u8]) -> usize {
0
}
#[inline]
const fn lut(c: u8) -> usize {
match c {
(b'0'..=b'9') => (c - b'0') as usize + 27,
(b'A'..=b'Z') => (c - b'A') as usize,
_ => unreachable!(),
}
}
fn main() {
for input in INPUTS.iter() {
println!("total = {}", process(input));

52
src/day8/2.rs
View File

@ -1,8 +1,6 @@
#![feature(slice_split_once)]
#![feature(test)]
use std::collections::HashMap;
extern crate test;
const INPUTS: [&[u8]; 2] = [
@ -13,8 +11,7 @@ const INPUTS: [&[u8]; 2] = [
fn process(data: &[u8]) -> usize {
let (seq, remain) = data.split_once(|&x| x == b'\n').unwrap();
let mut map = HashMap::new();
let mut map = vec![];
for line in remain.split(|&x| x == b'\n').skip(1) {
if line.is_empty() {
continue;
@ -22,28 +19,41 @@ fn process(data: &[u8]) -> usize {
let (start, remain) = line.split_at(3);
let (l, r) = (&remain[4..7], &remain[9..12]);
map.insert(start, (l, r));
// Pack data into 6 bytes each
let start = lut(start[0]) << 10 | lut(start[1]) << 5 | lut(start[2]);
let l = lut(l[0]) << 10 | lut(l[1]) << 5 | lut(l[2]);
let r = lut(r[0]) << 10 | lut(r[1]) << 5 | lut(r[2]);
if start >= map.len() {
map.extend(std::iter::repeat(None).take(start - map.len() + 1));
}
let mut a_set = vec![];
for &k in map
.keys()
.filter(|x| x.last().map_or(false, |&b| b == b'A'))
{
a_set.push(k);
map[start] = Some((l, r));
}
let mut tmp = Vec::with_capacity(a_set.len());
let mut set = vec![];
'outer: for mut node in a_set {
const A: usize = lut(b'A');
const Z: usize = lut(b'Z');
for (i, _) in map.iter().enumerate().filter(|(_, v)| v.is_some()) {
let last = i & 0b11_111;
if last == A {
set.push(i);
}
}
let mut tmp = Vec::with_capacity(set.len());
'outer: for mut node in set {
for (i, ins) in seq.iter().cycle().enumerate() {
if node.last().map_or(false, |&b| b == b'Z') {
let last = node & 0b11_111;
if last == Z {
tmp.push(i);
continue 'outer;
}
let (l, r) = map.get(node).unwrap();
let (l, r) = map[node].unwrap();
match ins {
b'L' => node = l,
@ -56,6 +66,16 @@ fn process(data: &[u8]) -> usize {
lcm(&tmp)
}
#[inline]
const fn lut(c: u8) -> usize {
match c {
(b'0'..=b'9') => (c - b'0') as usize + 27,
(b'A'..=b'Z') => (c - b'A') as usize,
_ => unreachable!(),
}
}
fn lcm(a: &[usize]) -> usize {
let mut answer = a[0];