|
| 1 | +use std::collections::HashSet; |
| 2 | + |
| 3 | +use anyhow::{Context, Ok, Result}; |
| 4 | +use itertools::Itertools; |
| 5 | +pub fn part1(input: &str) -> Result<usize> { |
| 6 | + let image = Image::parse_with_distance_factor(input, 2)?; |
| 7 | + let sum = sum_galaxies_distance(image); |
| 8 | + |
| 9 | + Ok(sum) |
| 10 | +} |
| 11 | + |
| 12 | +pub fn part2(input: &str) -> Result<usize> { |
| 13 | + let image = Image::parse_with_distance_factor(input, 1000000)?; |
| 14 | + let sum = sum_galaxies_distance(image); |
| 15 | + |
| 16 | + Ok(sum) |
| 17 | +} |
| 18 | + |
| 19 | +fn sum_galaxies_distance(image: Image) -> usize { |
| 20 | + image |
| 21 | + .galaxies |
| 22 | + .iter() |
| 23 | + .enumerate() |
| 24 | + .combinations(2) |
| 25 | + .map(|comb| image.get_distance(comb[0].0, comb[1].0)) |
| 26 | + .sum() |
| 27 | +} |
| 28 | + |
| 29 | +struct Image { |
| 30 | + galaxies: Vec<(usize, usize)>, |
| 31 | +} |
| 32 | + |
| 33 | +impl Image { |
| 34 | + fn parse_with_distance_factor(input: &str, distance_factor: usize) -> Result<Self> { |
| 35 | + let distance_factor = distance_factor - 1; |
| 36 | + |
| 37 | + let image = input |
| 38 | + .lines() |
| 39 | + .map(|line| line.chars().collect()) |
| 40 | + .collect::<Vec<Vec<char>>>(); |
| 41 | + |
| 42 | + let mut galaxies = vec![]; |
| 43 | + |
| 44 | + let mut image_iter = image.iter().peekable(); |
| 45 | + |
| 46 | + let all_empty_column = image_iter |
| 47 | + .peek() |
| 48 | + .context("empty image")? |
| 49 | + .iter() |
| 50 | + .enumerate() |
| 51 | + .filter(|(column, _)| { |
| 52 | + (0..image.len()) |
| 53 | + .map(|i| image[i][*column]) |
| 54 | + .all(|c| c == '.') |
| 55 | + }) |
| 56 | + .map(|(column, _)| column) |
| 57 | + .collect::<HashSet<usize>>(); |
| 58 | + |
| 59 | + let mut current_y = 0; |
| 60 | + for row in image_iter { |
| 61 | + let mut current_x = 0; |
| 62 | + for (x, c) in row.iter().enumerate() { |
| 63 | + if c == &'#' { |
| 64 | + galaxies.push((current_x, current_y)); |
| 65 | + } |
| 66 | + |
| 67 | + current_x += 1; |
| 68 | + |
| 69 | + if all_empty_column.contains(&x){ |
| 70 | + current_x += distance_factor; |
| 71 | + } |
| 72 | + } |
| 73 | + current_y += 1; |
| 74 | + |
| 75 | + if row.iter().all(|c| *c == '.') { |
| 76 | + current_y += distance_factor; |
| 77 | + } |
| 78 | + } |
| 79 | + |
| 80 | + Ok(Self { galaxies }) |
| 81 | + } |
| 82 | + |
| 83 | + fn get_distance(&self, source: usize, target: usize) -> usize { |
| 84 | + let (x1, y1) = self.galaxies[source]; |
| 85 | + let (x2, y2) = self.galaxies[target]; |
| 86 | + x1.max(x2) - x1.min(x2) + y1.max(y2) - y1.min(y2) |
| 87 | + } |
| 88 | +} |
| 89 | + |
| 90 | +#[cfg(test)] |
| 91 | +mod tests { |
| 92 | + use super::*; |
| 93 | + |
| 94 | + #[test] |
| 95 | + fn test_part1() { |
| 96 | + let input = include_str!("../example"); |
| 97 | + assert_eq!(part1(input).unwrap(), 374); |
| 98 | + } |
| 99 | + |
| 100 | + #[test] |
| 101 | + fn test_get_path() { |
| 102 | + let input = include_str!("../example"); |
| 103 | + let image = Image::parse_with_distance_factor(input, 2).unwrap(); |
| 104 | + |
| 105 | + assert_eq!(image.get_distance(4, 8), 9); |
| 106 | + assert_eq!(image.get_distance(0, 6), 15); |
| 107 | + } |
| 108 | + |
| 109 | + #[test] |
| 110 | + fn test_parse() { |
| 111 | + let input = include_str!("../example"); |
| 112 | + let image = Image::parse_with_distance_factor(input, 10).unwrap(); |
| 113 | + |
| 114 | + assert_eq!(sum_galaxies_distance(image), 1030); |
| 115 | + |
| 116 | + let image = Image::parse_with_distance_factor(input, 100).unwrap(); |
| 117 | + assert_eq!(sum_galaxies_distance(image), 8410); |
| 118 | + } |
| 119 | +} |
0 commit comments