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day20: trade memory for perf

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This commit is contained in:
Ishan Jain 2023-12-21 00:53:04 +05:30
parent 433d29d079
commit 85cc09aecc
Signed by: ishan
GPG Key ID: 0506DB2A1CC75C27
1 changed files with 23 additions and 19 deletions
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42
src/day20/2.rs
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@ -2,7 +2,7 @@
#![feature(byte_slice_trim_ascii)] #![feature(byte_slice_trim_ascii)]
#![feature(test)] #![feature(test)]
use std::collections::{HashMap, VecDeque}; use std::collections::VecDeque;
extern crate test; extern crate test;
const INPUTS: [&str; 1] = [include_str!("./input.txt")]; const INPUTS: [&str; 1] = [include_str!("./input.txt")];
@ -27,8 +27,8 @@ fn compress(mut c: &[u8]) -> usize {
fn process(data: &str) -> usize { fn process(data: &str) -> usize {
let data = data.as_bytes(); let data = data.as_bytes();
let mut map: HashMap<usize, (u8, Vec<usize>)> = HashMap::new(); let mut map = vec![];
let mut inverted_map: HashMap<usize, Vec<usize>> = HashMap::new(); let mut inverted_map = vec![];
for line in data.split(|&x| x == b'\n') { for line in data.split(|&x| x == b'\n') {
if line.is_empty() { if line.is_empty() {
@ -52,23 +52,27 @@ fn process(data: &str) -> usize {
.map(compress) .map(compress)
.collect(); .collect();
map.insert(label, (stype, dst)); if map.len() <= label {
map.extend(std::iter::repeat((0, vec![])).take(label - map.len() + 1));
} }
for (k, (_, dst)) in map.iter() { map[label] = (stype, dst);
}
inverted_map.extend(std::iter::repeat(vec![]).take(map.len() - inverted_map.len()));
for (k, (_, dst)) in map.iter().enumerate() {
for &dst in dst { for &dst in dst {
inverted_map.entry(dst).or_default().push(*k); inverted_map[dst].push(k);
} }
} }
let mut button_state = vec![false; map.keys().max().unwrap() + 1]; let mut button_state = vec![false; map.len() + 1];
let mut button_presses = vec![]; let mut button_presses = vec![];
let mut button_press = 0; let mut button_press = 0;
let rx_input = *inverted_map let rx_input = *inverted_map[compress("rx".as_bytes())]
.get(&compress("rx".as_bytes()))
.unwrap()
.iter() .iter()
.next() .next()
.unwrap(); .unwrap();
@ -84,7 +88,7 @@ fn process(data: &str) -> usize {
rx_input, rx_input,
); );
if button_presses.len() == inverted_map.get(&rx_input).map_or(0, |x| x.len()) { if button_presses.len() == inverted_map[rx_input].len() {
break; break;
} }
} }
@ -113,14 +117,14 @@ const fn gcd(a: usize, b: usize) -> usize {
fn cycle( fn cycle(
button_press: usize, button_press: usize,
state: &mut [bool], state: &mut [bool],
map: &HashMap<usize, (u8, Vec<usize>)>, map: &[(u8, Vec<usize>)],
inverted_map: &HashMap<usize, Vec<usize>>, inverted_map: &[Vec<usize>],
button_presses: &mut Vec<usize>, button_presses: &mut Vec<usize>,
rx_input: usize, rx_input: usize,
) { ) {
let mut q = VecDeque::new(); let mut q = VecDeque::new();
let (_, broadcast_dst) = map.get(&compress("broadcaster".as_bytes())).unwrap(); let (_, broadcast_dst) = &map[compress("broadcaster".as_bytes())];
for &dst in broadcast_dst { for &dst in broadcast_dst {
q.push_back((dst, false)); q.push_back((dst, false));
} }
@ -130,11 +134,11 @@ fn cycle(
button_presses.push(button_press); button_presses.push(button_press);
continue; continue;
} }
let (dtype, dnext) = match map.get(&dst) {
Some(v) => v,
None => continue,
};
let (dtype, dnext) = &map[dst];
if *dtype == 0 {
continue;
}
match dtype { match dtype {
b'%' => { b'%' => {
if pulse { if pulse {
@ -148,7 +152,7 @@ fn cycle(
} }
b'&' => { b'&' => {
let new_state = inverted_map.get(&dst).unwrap().iter().all(|&x| state[x]); let new_state = inverted_map[dst].iter().all(|&x| state[x]);
for &next in dnext { for &next in dnext {
q.push_back((next, !new_state)); q.push_back((next, !new_state));