75 lines
2.9 KiB
Rust
75 lines
2.9 KiB
Rust
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use std::io::{self, BufRead};
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const ADD_TO_EMPTY1: usize = 1;
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const ADD_TO_EMPTY2: usize = 1_000_000-1;
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fn add_empty_columns(galaxy_positions: &mut Vec<(usize, usize)>, add_to_empty: usize) {
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let mut last_x: usize = galaxy_positions[0].0;
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let mut empty_columns: usize = 0;
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for i in 1..galaxy_positions.len() {
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if galaxy_positions[i].0 > last_x + 1 {
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empty_columns += (galaxy_positions[i].0 - last_x - 1) * add_to_empty;
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}
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last_x = galaxy_positions[i].0;
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galaxy_positions[i].0 += empty_columns;
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}
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}
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fn get_distance_sum(galaxy_positions: &Vec<(usize, usize)>) -> usize {
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let mut distance_sum: usize = 0;
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for i in 0..galaxy_positions.len() - 1 {
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for j in i+1..galaxy_positions.len() {
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// println!("{}<->{}: {}", i, j, galaxy_positions[i].0.abs_diff(galaxy_positions[j].0) + galaxy_positions[i].1.abs_diff(galaxy_positions[j].1));
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distance_sum += galaxy_positions[i].0.abs_diff(galaxy_positions[j].0);
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distance_sum += galaxy_positions[i].1.abs_diff(galaxy_positions[j].1);
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}
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}
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return distance_sum;
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}
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fn main() {
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// let input = "example.txt";
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let input = "input.txt";
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let lines = read_lines(&input);
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let mut galaxy_positions1: Vec<(usize, usize)> = Vec::new();
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let mut galaxy_positions2: Vec<(usize, usize)> = Vec::new();
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galaxy_positions1.reserve(300);
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galaxy_positions2.reserve(300);
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let mut y1: usize = 0;
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let mut y2: usize = 0;
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for line in lines.map(|r| r.ok().unwrap()) {
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let mut galaxies = line.chars().enumerate().filter(|(_, c)| *c == '#');
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if let Some((x, _)) = galaxies.next() {
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galaxy_positions1.push((x, y1));
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galaxy_positions2.push((x, y2));
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while let Some((x, _)) = galaxies.next() {
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galaxy_positions1.push((x, y1));
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galaxy_positions2.push((x, y2));
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}
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}
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else { // empty lines are double the size
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y1 += ADD_TO_EMPTY1;
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y2 += ADD_TO_EMPTY2;
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}
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y1 += 1;
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y2 += 1;
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}
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// sort by x
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galaxy_positions1.sort_unstable_by(|a ,b| a.0.cmp(&b.0));
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galaxy_positions2.sort_unstable_by(|a ,b| a.0.cmp(&b.0));
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add_empty_columns(&mut galaxy_positions1, ADD_TO_EMPTY1);
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add_empty_columns(&mut galaxy_positions2, ADD_TO_EMPTY2);
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let distance_sum1: usize = get_distance_sum(&galaxy_positions1);
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println!("Sum of galaxy distances: (1): {}", distance_sum1);
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let distance_sum2: usize = get_distance_sum(&galaxy_positions2);
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println!("Sum of galaxy distances: (2): {}", distance_sum2);
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}
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fn read_lines<P>(filename: P) -> io::Lines<io::BufReader<std::fs::File>>
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where P: AsRef<std::path::Path>, {
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return match std::fs::File::open(filename) {
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Err(why) => panic!("Could not open file. {}", why),
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Ok(file) => std::io::BufReader::new(file).lines()
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};
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}
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