rust(day23): Rust too

This commit is contained in:
Sijmen 2020-12-25 02:15:25 +01:00
parent 050cd4e1be
commit cd901b2fc5
Signed by: vijfhoek
GPG Key ID: DAF7821E067D9C48
3 changed files with 103 additions and 0 deletions

2
.gitignore vendored
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@ -1,4 +1,6 @@
rust/target
callgrind.*
*.prof
c64/*.vs
c64/*.prg

91
rust/src/day23.rs Normal file
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@ -0,0 +1,91 @@
use std::{time::Duration, time::Instant};
fn step(cups: &mut [u32], current_label: u32, min: u32, max: u32) -> u32 {
let a = cups[current_label as usize];
let b = cups[a as usize];
let c = cups[b as usize];
let picked_up = &[a, b, c];
cups[current_label as usize] = cups[c as usize];
let mut destination = current_label - 1;
if destination < min {
destination = max;
}
while picked_up.contains(&destination) {
destination -= 1;
if destination < min {
destination = max;
}
}
cups[c as usize] = cups[destination as usize];
cups[destination as usize] = a;
cups[current_label as usize]
}
fn part1(labels: &[u32]) -> Option<u32> {
let mut cups = vec![0; labels.len() + 1];
for i in 0..labels.len() {
cups[labels[i] as usize] = labels[(i + 1) % labels.len()];
}
let mut current = labels[0];
let min = labels.iter().min()?;
let max = labels.iter().max()?;
for _ in 0..100 {
current = step(&mut cups, current, *min, *max);
}
let mut result = 0;
let mut label = 1;
for _ in 0..8 {
label = cups[label as usize];
result = result * 10 + label;
}
Some(result)
}
fn part2(old_labels: &[u32]) -> Option<usize> {
let mut labels = Vec::from(old_labels);
labels.reserve(1_000_000);
labels.extend((*old_labels.iter().max()? + 1)..=1_000_000);
let cups = &mut [0; 1_000_001];
for i in 0..labels.len() {
cups[labels[i] as usize] = labels[(i + 1) % labels.len()];
}
let mut current = labels[0];
let min = labels.iter().min()?;
let max = labels.iter().max()?;
for _ in 0..10_000_000 {
current = step(cups, current, *min, *max);
}
let a = cups[1] as usize;
let b = cups[a as usize] as usize;
Some(a * b)
}
pub fn run(print: bool) -> Duration {
let file_string = std::fs::read_to_string("../inputs/23").unwrap();
let instant = Instant::now();
let labels: Vec<u32> = file_string
.trim()
.chars()
.map(|c| (c as u32 - '0' as u32))
.collect();
let part1 = part1(&labels).unwrap();
let part2 = part2(&labels).unwrap();
if print {
dbg!(part1, part2);
}
instant.elapsed()
}

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@ -22,6 +22,11 @@ mod day17;
use nop as day18;
mod day19;
use nop as day20;
use nop as day21;
use nop as day22;
mod day23;
use nop as day24;
use nop as day25;
fn main() {
let days = [
@ -45,6 +50,11 @@ fn main() {
day18::run,
day19::run,
day20::run,
day21::run,
day22::run,
day23::run,
day24::run,
day25::run,
];
if let Some(day) = std::env::args().nth(1) {