2020: day17: part 1

This commit is contained in:
Antoine Martin 2020-12-17 13:12:11 +01:00
parent 8236dbc0c2
commit e18b6edf80
8 changed files with 128 additions and 0 deletions

1
Cargo.lock generated
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@ -68,6 +68,7 @@ version = "0.1.0"
dependencies = [
"anyhow",
"aoc",
"itertools",
]
[[package]]

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@ -9,6 +9,7 @@ edition = "2018"
[dependencies]
aoc = { path = "../aoc" }
anyhow = "1.0"
itertools = "0.9"
[lib]
path = "src/lib.rs"

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@ -16,6 +16,7 @@ use aoc2020::day13;
use aoc2020::day14;
use aoc2020::day15;
use aoc2020::day16;
use aoc2020::day17;
fn aoc2020_all(c: &mut Criterion) {
c.bench_function("day01", |b| b.iter(|| day01::run().unwrap()));
@ -34,6 +35,7 @@ fn aoc2020_all(c: &mut Criterion) {
c.bench_function("day14", |b| b.iter(|| day14::run().unwrap()));
c.bench_function("day15", |b| b.iter(|| day15::run().unwrap()));
c.bench_function("day16", |b| b.iter(|| day16::run().unwrap()));
c.bench_function("day17", |b| b.iter(|| day17::run().unwrap()));
}
criterion_group! {

8
aoc2020/input/day17.txt Normal file
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@ -0,0 +1,8 @@
#####..#
#..###.#
###.....
.#.#.#..
##.#..#.
######..
.##..###
###.####

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@ -0,0 +1,3 @@
.#.
..#
###

110
aoc2020/src/day17.rs Normal file
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@ -0,0 +1,110 @@
use std::collections::HashSet;
use std::fmt::Write;
use anyhow::{anyhow, Result};
use itertools::iproduct;
const INPUT: &str = include_str!("../input/day17.txt");
pub fn run() -> Result<String> {
let mut res = String::with_capacity(128);
writeln!(res, "part 1: {}", part1(INPUT)?)?;
Ok(res)
}
fn part1(input: &str) -> Result<usize> {
let mut pocket_dim: PocketDimension = input.parse()?;
for _ in 0..6 {
pocket_dim.update();
}
Ok(pocket_dim.points.len())
}
type Point = (i64, i64, i64);
struct PocketDimension {
points: HashSet<Point>,
}
impl PocketDimension {
fn neighbours(point: Point) -> impl Iterator<Item = Point> {
iproduct!(-1..=1, -1..=1, -1..=1)
.filter(|(x, y, z)| *x != 0 || *y != 0 || *z != 0)
.map(move |(dx, dy, dz)| (point.0 + dx, point.1 + dy, point.2 + dz))
}
fn active_neighbours(&self, point: Point) -> usize {
Self::neighbours(point)
.filter(|p| self.points.contains(p))
.count()
}
fn update(&mut self) {
let mut processed: HashSet<Point> = HashSet::new();
let mut new = self.points.clone();
for point in &self.points {
for neighbour in Self::neighbours(*point).chain(std::iter::once(*point)) {
if processed.contains(&neighbour) {
continue;
}
processed.insert(neighbour);
// if point is active
if self.points.contains(&neighbour) {
if !(2..=3).contains(&self.active_neighbours(neighbour)) {
// now inactive
new.remove(&neighbour);
}
} else if self.active_neighbours(neighbour) == 3 {
new.insert(neighbour);
}
}
}
self.points = new;
}
}
impl std::str::FromStr for PocketDimension {
type Err = anyhow::Error;
fn from_str(s: &str) -> Result<Self> {
let points = s
.lines()
.enumerate()
.flat_map(|(i, line)| {
line.chars().enumerate().filter_map(move |(j, c)| match c {
'#' => Some(Ok((i as i64, j as i64, 0))),
'.' => None,
_ => Some(Err(anyhow!("unexpected char: `{}`", c))),
})
})
.collect::<Result<_>>()?;
Ok(Self { points })
}
}
#[cfg(test)]
mod tests {
use super::*;
const PROVIDED: &str = include_str!("../input/day17_provided.txt");
#[test]
fn part1_provided() {
assert_eq!(part1(PROVIDED).unwrap(), 112);
}
#[test]
fn part1_real() {
assert_eq!(part1(INPUT).unwrap(), 336);
}
}

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@ -16,3 +16,4 @@ pub mod day13;
pub mod day14;
pub mod day15;
pub mod day16;
pub mod day17;

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@ -18,6 +18,7 @@ use aoc2020::day13;
use aoc2020::day14;
use aoc2020::day15;
use aoc2020::day16;
use aoc2020::day17;
fn main() -> Result<()> {
let days: &[DayFunc] = &[
@ -37,6 +38,7 @@ fn main() -> Result<()> {
day14::run,
day15::run,
day16::run,
day17::run,
];
aoc::run(days)