forked from ggriffiniii/aoc
102 lines
2.8 KiB
Rust
102 lines
2.8 KiB
Rust
use aoc_runner_derive::aoc;
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use std::collections::HashSet;
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#[aoc(day17, part1)]
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fn solve_d17_p1(input: &str) -> usize {
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let mut world = HashSet::new();
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for (y, line) in input.split('\n').enumerate() {
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for (x, _) in line
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.as_bytes()
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.iter()
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.copied()
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.enumerate()
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.filter(|&(_, byte)| byte == b'#')
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{
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world.insert((x as isize, y as isize, 0isize, 0isize));
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}
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}
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for _ in 0..6 {
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world = step(world);
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}
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world.len()
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}
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fn neighbors(
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world: &HashSet<(isize, isize, isize, isize)>,
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(x, y, z, w): (isize, isize, isize, isize),
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) -> usize {
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let mut count = 0;
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for xa in x - 1..=x + 1 {
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for ya in y - 1..=y + 1 {
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for za in z - 1..=z + 1 {
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for wa in w - 1..=w + 1 {
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count += world.contains(&(xa, ya, za, wa)) as usize;
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}
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}
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}
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}
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count - world.contains(&(x, y, z, w)) as usize
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}
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fn step(world: HashSet<(isize, isize, isize, isize)>) -> HashSet<(isize, isize, isize, isize)> {
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struct MinMax {
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x_min: isize,
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x_max: isize,
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y_min: isize,
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y_max: isize,
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z_min: isize,
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z_max: isize,
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w_min: isize,
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w_max: isize,
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}
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let MinMax {
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x_min,
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x_max,
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y_min,
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y_max,
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z_min,
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z_max,
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w_min,
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w_max,
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} = world.iter().fold(
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MinMax {
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x_min: isize::MAX,
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x_max: isize::MIN,
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y_min: isize::MAX,
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y_max: isize::MIN,
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z_min: isize::MAX,
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z_max: isize::MIN,
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w_min: isize::MAX,
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w_max: isize::MIN,
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},
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|minmax, &(x, y, z, w)| MinMax {
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x_min: std::cmp::min(minmax.x_min, x),
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x_max: std::cmp::max(minmax.x_max, x),
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y_min: std::cmp::min(minmax.y_min, y),
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y_max: std::cmp::max(minmax.y_max, y),
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z_min: std::cmp::min(minmax.z_min, z),
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z_max: std::cmp::max(minmax.z_max, z),
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w_min: std::cmp::min(minmax.w_min, w),
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w_max: std::cmp::max(minmax.w_max, w),
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},
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);
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let mut new_world = HashSet::new();
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for x in x_min - 1..=x_max + 1 {
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for y in y_min - 1..=y_max + 1 {
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for z in z_min - 1..=z_max + 1 {
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for w in w_min - 1..=w_max + 1 {
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let active = world.contains(&(x, y, z, w));
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let n = neighbors(&world, (x, y, z, w));
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if active && (n == 2 || n == 3) {
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new_world.insert((x, y, z, w));
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}
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if !active && n == 3 {
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new_world.insert((x, y, z, w));
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}
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}
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}
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}
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}
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new_world
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}
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