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use advent_lib::prelude::*;
fn main() -> Result<()> {
let mut args = std::env::args();
if args.len() != 2 {
eprintln!("Usage: advent input");
}
let _ = args.next();
let filename = args.next().unwrap();
let input = advent_lib::read_lines_file(&filename)?;
let mut iterator = input.iter();
let mut dictionary = Vec::new();
for c in iterator.next().unwrap().chars() {
dictionary.push(match c {
'#' => 1,
'.' => 0,
_ => panic!("unexpected character"),
});
}
let _ = iterator.next();
let mut image = Vec::new();
for line in iterator {
let mut row = Vec::new();
for c in line.chars() {
row.push(match c {
'#' => 1,
'.' => 0,
_ => panic!("unexpected character"),
});
}
image.push(row);
}
let mut background = 0;
for _ in 0 .. 2 {
let (new_image, new_background) =
iterate(&image, background, &dictionary);
image = new_image;
background = new_background;
}
println!("{}", count_pixels(&image));
for _ in 2 .. 50 {
let (new_image, new_background) =
iterate(&image, background, &dictionary);
image = new_image;
background = new_background;
}
println!("{}", count_pixels(&image));
Ok(())
}
fn iterate(input: &Vec<Vec<u8>>, background: u8, dictionary: &Vec<u8>)
-> (Vec<Vec<u8>>, u8)
{
let height = input.len() as i64;
let width = input[0].len() as i64;
let mut output = Vec::new();
for y in -2 .. height+2 {
let mut row = Vec::new();
for x in -2 .. width+2 {
let mut index: usize = 0;
for offset_y in -1 .. 2 {
for offset_x in -1 .. 2 {
let computed_y: i64 = y + offset_y;
let computed_x: i64 = x + offset_x;
index *= 2;
if (computed_y >= 0) && (computed_y < height)
&& (computed_x >= 0) && (computed_x < width)
{
index += input[computed_y as usize][computed_x as usize] as usize;
} else {
index += background as usize;
}
}
}
row.push(dictionary[index]);
}
output.push(row);
}
let output_background = dictionary[background as usize];
(output, output_background)
}
fn count_pixels(image: &Vec<Vec<u8>>) -> i64 {
let mut count = 0;
for row in image {
for cell in row {
count += *cell as i64;
}
}
count
}
#[allow(dead_code)]
fn debug_image(image: &Vec<Vec<u8>>) {
for row in image {
for cell in row {
if *cell == 1 {
print!("#");
} else {
print!(".");
}
}
println!("");
}
println!("");
}
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