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use std::ops::Range;
const INPUT: &str = include_str!("../../data/day17");
#[derive(Clone, Copy, Default)]
struct Dimension {
offset: u32,
size: u32,
}
impl Dimension {
fn map(&self, pos: i32) -> Option<usize> {
let p = (self.offset as i32) + pos;
if p >= 0 && p < (self.size as i32) {
Some(p as usize)
} else {
None
}
}
fn include(&self, pos: i32) -> Self {
let left = std::cmp::min(pos, -(self.offset as i32));
let right = std::cmp::max(pos, (self.size - self.offset - 1) as i32);
Self {
offset: (-left) as u32,
size: (right - left + 1) as u32,
}
}
fn extend(&self) -> Self {
Self {
offset: self.offset + 1,
size: self.size + 2,
}
}
}
impl IntoIterator for Dimension {
type IntoIter = Range<i32>;
type Item = i32;
fn into_iter(self) -> Self::IntoIter {
-(self.offset as i32)..((self.size - self.offset) as i32)
}
}
#[derive(Clone)]
struct Field {
x_dim: Dimension,
y_dim: Dimension,
z_dim: Dimension,
w_dim: Dimension,
cells: Vec<bool>,
}
impl Default for Field {
fn default() -> Self {
Self {
x_dim: Dimension { offset: 0, size: 1},
y_dim: Dimension { offset: 0, size: 1},
z_dim: Dimension { offset: 0, size: 1},
w_dim: Dimension { offset: 0, size: 1},
cells: vec![false],
}
}
}
impl Field {
fn alloc(x_dim: Dimension, y_dim: Dimension, z_dim: Dimension, w_dim: Dimension) -> Self {
let mut cells = Vec::new();
let size = (x_dim.size * y_dim.size * z_dim.size * w_dim.size) as usize;
cells.resize(size, false);
Self { x_dim, y_dim, z_dim, w_dim, cells }
}
fn _addr(&self, x: i32, y: i32, z: i32, w: i32) -> Option<usize> {
let x = self.x_dim.map(x)?;
let y = self.y_dim.map(y)?;
let z = self.z_dim.map(z)?;
let w = self.w_dim.map(w)?;
let addr = ((w * (self.z_dim.size as usize) + z) * (self.y_dim.size as usize) + y) * (self.x_dim.size as usize) + x;
Some(addr)
}
fn _get(&self, x: i32, y: i32, z: i32, w: i32) -> Option<bool> {
let addr = self._addr(x, y, z, w)?;
Some(self.cells[addr])
}
fn get(&self, x: i32, y: i32, z: i32, w: i32) -> bool {
self._get(x, y, z, w).unwrap_or(false)
}
fn set(&mut self, x: i32, y: i32, z: i32, w: i32, value: bool) {
if let Some(addr) = self._addr(x, y, z, w) {
self.cells[addr] = value;
} else if value {
// don't resize to set "false"
let x_dim = self.x_dim.include(x);
let y_dim = self.y_dim.include(y);
let z_dim = self.z_dim.include(z);
let w_dim = self.w_dim.include(w);
let mut new_field = Self::alloc(x_dim, y_dim, z_dim, w_dim);
for w in self.w_dim {
for z in self.z_dim {
for y in self.y_dim {
for x in self.x_dim {
let addr = new_field._addr(x, y, z, w).unwrap();
new_field.cells[addr] = self.get(x, y, z, w);
}
}
}
}
let addr = new_field._addr(x, y, z, w).unwrap();
new_field.cells[addr] = value;
*self = new_field;
}
}
fn parse(data: &str) -> Self {
let mut this = Self::default();
for (y, line) in data.lines().enumerate() {
for (x, chr) in line.chars().enumerate() {
this.set(x as i32, y as i32, 0, 0, chr == '#');
}
}
this
}
fn count_active_neighbors(&self, x: i32, y: i32, z: i32, w: i32) -> u32 {
let mut count = 0;
for dw in -1..=1 {
for dz in -1..=1 {
for dy in -1..=1 {
for dx in -1..=1 {
if dw == 0 && dz == 0 && dy == 0 && dx == 0 {
continue;
}
if self.get(x + dx, y + dy, z + dz, w + dw) {
count += 1;
if count > 3 { return count; } // more than 3 is always bad
}
}
}
}
}
count
}
fn cycle_3dim(&self) -> Self {
let mut result = self.clone();
let w = 0;
for z in self.z_dim.extend() {
for y in self.y_dim.extend() {
for x in self.x_dim.extend() {
let count = self.count_active_neighbors(x, y, z, w);
let active = count == 3 || (count == 2 && self.get(x, y, z, w));
result.set(x, y, z, w, active);
}
}
}
result
}
fn cycle_4dim(&self) -> Self {
let mut result = self.clone();
for w in self.w_dim.extend() {
for z in self.z_dim.extend() {
for y in self.y_dim.extend() {
for x in self.x_dim.extend() {
let count = self.count_active_neighbors(x, y, z, w);
let active = count == 3 || (count == 2 && self.get(x, y, z, w));
result.set(x, y, z, w, active);
}
}
}
}
result
}
}
impl std::fmt::Debug for Field {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
use std::fmt::Write;
for z in self.z_dim {
for w in self.w_dim {
writeln!(f, "z = {}, w = {}", z, w)?;
for y in self.y_dim {
for x in self.x_dim {
if x == 0 && y == 0 {
f.write_char(
if self.get(x, y, z, w) { 'X' } else { '+' }
)?;
} else {
f.write_char(
if self.get(x, y, z, w) { '#' } else { '.' }
)?;
}
}
f.write_char('\n')?;
}
f.write_char('\n')?;
}
}
Ok(())
}
}
fn main() {
let input = Field::parse(INPUT);
let mut field = input.clone();
for _ in 0..6 {
field = field.cycle_3dim();
}
println!("Active after 6 3-dim rounds: {}", field.cells.iter().filter(|&&c| c).count());
let mut field = input.clone();
for _ in 0..6 {
field = field.cycle_4dim();
}
println!("Active after 6 4-dim rounds: {}", field.cells.iter().filter(|&&c| c).count());
println!("{:?}", input);
}