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use std::fs;
use std::path::Path;
use std::collections::VecDeque;
use std::fmt::Display;
use std::fmt::Formatter;
use std::fmt::Result;
#[derive(Debug)]
struct Map {
step: usize,
pixels: VecDeque<VecDeque<u8>>
}
impl Map {
fn pad(&mut self, pix: u8) {
let h = self.pixels.len();
let w = self.pixels[0].len();
let pix = if pix == 0 { 0 } else { u8::MAX };
if self.pixels[h-1].iter().any(|&b| b > 0) || self.pixels[h-2].iter().any(|&b| b > 0) {
let empty = VecDeque::from([pix].repeat(w));
self.pixels.push_back(empty.clone());
self.pixels.push_back(empty);
}
if self.pixels[0].iter().any(|&b| b > 0) || self.pixels[1].iter().any(|&b| b > 0) {
let empty = VecDeque::from([pix].repeat(w));
self.pixels.push_front(empty.clone());
self.pixels.push_front(empty);
}
if self.pixels.iter().any(|v| v[w-1] & 3 != 0) {
self.pixels.iter_mut().for_each(|v| v.push_back(pix));
}
if self.pixels.iter().any(|v| v[0] >= (1<<6)) {
self.pixels.iter_mut().for_each(|v| v.push_front(pix));
}
}
fn enhance(mut self, algorithm: &[u8]) -> Map {
let padpix = if algorithm[0] == 0 { 0 } else { algorithm[[algorithm.len()-1,0][self.step % 2]] };
self.pad(padpix);
let h = self.pixels.len();
let w = self.pixels[0].len();
let mut pixels = VecDeque::with_capacity(h);
for i in 0..h {
let mut row = VecDeque::with_capacity(w);
for j in 0..w {
let mut byte = 0;
for p in 0..8 {
let pix = {
if i < 1 || i > h-2 || (j < 1 && p < 1 ) || (j > w-2 && p > 6) {
if algorithm[0] == 0 { 0 } else { algorithm[[0,algorithm.len()-1][self.step % 2]] }
} else {
algorithm[self.index(i,8*j+p)]
}
};
byte = (byte<<1) | pix;
}
row.push_back(byte);
}
pixels.push_back(row);
}
Map { step: self.step+1, pixels }
}
fn pix(&self, y: usize, x: usize) -> u8 {
(self.pixels[y][x/8] >> (7-x%8)) & 1
}
fn index(&self, y: usize, x: usize) -> usize {
let mut idx = 0;
for i in y-1..y+2 {
for j in x-1..x+2 {
idx = (idx << 1) | self.pix(i,j) as usize
}
}
idx
}
fn lights(&self) -> u32 {
self.pixels.iter().flat_map(|v| v.iter().map(|&b| b.count_ones())).sum()
}
}
impl Display for Map {
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
self.pixels.iter().for_each(|v| {
v.iter().for_each(|b| write!(f, "{}", format!("{:08b}",b).chars().map(|c| if c == '1' { '#' } else { '.' }).collect::<String>()).unwrap());
write!(f, "\n").unwrap()
});
Ok(())
}
}
fn main() {
let input = Path::new("resources").join("input.txt");
let content = fs::read_to_string(input).expect("Unable to read input file");
let (mut map, algorithm) = parse_input(&content);
map = map.enhance(&algorithm).enhance(&algorithm);
println!("Ex1: The result is {}", map.lights());
for _ in 0..50-2 {
map = map.enhance(&algorithm);
}
println!("Ex2: The result is {}", map.lights());
}
fn parse_input(input: &str) -> (Map, Vec<u8>) {
let (algorithm,pixels) = input.split_once("\n\n").expect("Malformed input");
let algorithm: Vec<u8> = algorithm.chars().map(|c| (c == '#') as u8).collect();
let pixels: VecDeque<VecDeque<u8>> = pixels.lines().map(|l| {
let bits: Vec<u8> = l.chars().map(|c| (c == '#') as u8).collect();
bits.chunks(8).map(|c| c.iter().fold(0, |a,b| (a<<1)|b) << (8-c.len())).collect()
}).collect();
(Map { step: 0, pixels }, algorithm)
}
#[cfg(test)]
mod tests {
use super::*;
const INPUT: &str = "..#.#..#####.#.#.#.###.##.....###.##.#..###.####..#####..#....#..#..##..###..######.###...####..#..#####..##..#.#####...##.#.#..#.##..#.#......#.###.######.###.####...#.##.##..#..#..#####.....#.#....###..#.##......#.....#..#..#..##..#...##.######.####.####.#.#...#.......#..#.#.#...####.##.#......#..#...##.#.##..#...##.#.##..###.#......#.#.......#.#.#.####.###.##...#.....####.#..#..#.##.#....##..#.####....##...##..#...#......#.#.......#.......##..####..#...#.#.#...##..#.#..###..#####........#..####......#..#
#..#.
#....
##..#
..#..
..###";
#[test]
fn input_parse() {
let (mut map,algorithm) = parse_input(INPUT);
println!("{}", map);
map = map.enhance(&algorithm);
println!("{}", map);
map = map.enhance(&algorithm);
println!("{}", map);
assert_eq!(35, map.lights());
}
}
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