112 lines
3.1 KiB
Rust
112 lines
3.1 KiB
Rust
use std::collections::{HashMap, HashSet};
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use std::error::Error;
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use std::fs::File;
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use std::io::{self, BufRead};
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use std::vec::Vec;
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#[derive(PartialEq, Copy, Clone, Debug)]
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enum CubeState {
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Active,
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Inactive,
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}
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fn enumerate_adjacent(x: i32, y: i32, z: i32) -> Vec<(i32, i32, i32)> {
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let mut res: Vec<(i32, i32, i32)> = Vec::new();
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for dx in -1..2 {
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for dy in -1..2 {
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for dz in -1..2 {
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if dx != 0 || dy != 0 || dz != 0 {
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res.push((x + dx, y + dy, z + dz));
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}
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}
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}
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}
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res
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}
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fn count_adjacent_active(
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x: i32,
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y: i32,
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z: i32,
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world: &HashMap<(i32, i32, i32), CubeState>,
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) -> u32 {
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enumerate_adjacent(x, y, z)
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.iter()
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.map(|coords| match world.get(&coords) {
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Some(CubeState::Active) => 1,
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_ => 0,
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})
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.fold(0u32, |x, acc| x + acc)
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}
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fn main() -> Result<(), Box<dyn Error>> {
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let file = File::open("inputs/day17.txt")?;
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let lines = io::BufReader::new(file).lines().map(|l| l.unwrap());
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let mut world: HashMap<(i32, i32, i32), CubeState> = HashMap::new();
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let initial_slice: Vec<(i32, i32, i32, CubeState)> = lines
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.enumerate()
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.map(|(y, l)| {
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l.chars()
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.enumerate()
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.map(|(x, c)| match c {
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'#' => (x as i32, y as i32, 0, CubeState::Active),
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'.' => (x as i32, y as i32, 0, CubeState::Inactive),
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_ => panic!("Unknown State: {}", c),
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})
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.collect::<Vec<(i32, i32, i32, CubeState)>>()
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})
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.fold(Vec::new(), |mut acc, mut x| {
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acc.append(&mut x);
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acc
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});
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for (x, y, z, s) in initial_slice {
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world.insert((x, y, z), s);
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}
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for _ in 0..6 {
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let mut used_positions: HashSet<(i32, i32, i32)> = HashSet::new();
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for (x, y, z) in world.keys() {
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for coords in enumerate_adjacent(*x, *y, *z) {
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used_positions.insert(coords);
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}
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}
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let mut new_world: HashMap<(i32, i32, i32), CubeState> = HashMap::new();
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for (x, y, z) in used_positions {
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let cur_state = if let Some(state) = world.get(&(x, y, z)) {
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*state
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} else {
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CubeState::Inactive
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};
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let active_adjacent = count_adjacent_active(x, y, z, &world);
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if cur_state == CubeState::Active && (active_adjacent == 2 || active_adjacent == 3) {
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new_world.insert((x, y, z), CubeState::Active);
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} else if cur_state == CubeState::Inactive && active_adjacent == 3 {
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new_world.insert((x, y, z), CubeState::Active);
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} else {
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new_world.insert((x, y, z), CubeState::Inactive);
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};
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}
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world = new_world;
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}
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let active_count = world
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.values()
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.map(|s| match s {
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CubeState::Active => 1,
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_ => 0,
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})
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.fold(0, |acc, x| x + acc);
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println!("Active Cells: {}", active_count);
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Ok(())
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}
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