[2023] Complete day 11

README.md

@@ -15,6 +15,7 @@ Thank you to [Eric Wastl](http://was.tl) for running this incredible yearly even
 - [Day 08: Haunted Wasteland](aoc_2023/src/day_08.rs)
 - [Day 09: Mirage Maintenance](aoc_2023/src/day_09.rs)
 - [Day 10: Pipe Maze](aoc_2023/src/day_10.rs)
+- [Day 11: Cosmic Expansion](aoc_2023/src/day_11.rs)
 <!-- MARKER -->
 
 ## [2022](https://adventofcode.com/2022) [![aoc_2022](https://github.com/Basicprogrammer10/advent-of-code/actions/workflows/aoc_2022.yml/badge.svg)](https://github.com/Basicprogrammer10/advent-of-code/actions/workflows/aoc_2022.yml)

aoc_2023/src/day_11.rs

@@ -0,0 +1,123 @@
+use itertools::Itertools;
+use nd_vec::{vector, Vec2};
+
+use common::{Answer, Solution};
+
+type Pos = Vec2<usize>;
+
+pub struct Day11;
+
+impl Solution for Day11 {
+    fn name(&self) -> &'static str {
+        "Cosmic Expansion"
+    }
+
+    fn part_a(&self, input: &str) -> Answer {
+        let mut galaxies = parse(input);
+        galaxies.expand(2);
+        galaxies.total_distance().into()
+    }
+
+    fn part_b(&self, input: &str) -> Answer {
+        let mut galaxies = parse(input);
+        galaxies.expand(1000000);
+        galaxies.total_distance().into()
+    }
+}
+
+struct Galaxies {
+    galaxies: Vec<Pos>,
+    rows: Vec<bool>,
+    cols: Vec<bool>,
+}
+
+fn parse(input: &str) -> Galaxies {
+    let mut galaxies = Vec::new();
+    let (height, width) = (input.lines().count(), input.lines().next().unwrap().len());
+
+    let mut rows = vec![false; height];
+    let mut cols = vec![false; width];
+
+    for (y, line) in input.lines().enumerate() {
+        for (x, c) in line.chars().enumerate() {
+            if c == '#' {
+                galaxies.push(vector!(x, y));
+                rows[y] = true;
+                cols[x] = true;
+            }
+        }
+    }
+
+    Galaxies {
+        galaxies,
+        rows,
+        cols,
+    }
+}
+
+impl Galaxies {
+    fn expand(&mut self, mut multiplier: usize) {
+        multiplier -= 1;
+
+        for (y, _) in self.rows.iter().enumerate().rev().filter(|(_, &row)| !row) {
+            for pos in &mut self.galaxies {
+                if pos.y() > y {
+                    *pos += vector!(0, multiplier)
+                }
+            }
+        }
+
+        for (x, _) in self.cols.iter().enumerate().rev().filter(|(_, &col)| !col) {
+            for pos in &mut self.galaxies {
+                if pos.x() > x {
+                    *pos += vector!(multiplier, 0)
+                }
+            }
+        }
+    }
+
+    fn total_distance(&self) -> usize {
+        self.galaxies
+            .iter()
+            .combinations(2)
+            .map(|pair| {
+                let (a, b) = (pair[0], pair[1]);
+                let dist = (a.x() as isize - b.x() as isize).abs()
+                    + (a.y() as isize - b.y() as isize).abs();
+
+                dist as usize
+            })
+            .sum()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use common::Solution;
+    use indoc::indoc;
+
+    use super::Day11;
+
+    const CASE: &str = indoc! {"
+        ...#......
+        .......#..
+        #.........
+        ..........
+        ......#...
+        .#........
+        .........#
+        ..........
+        .......#..
+        #...#.....
+    "};
+
+    #[test]
+    fn part_a() {
+        assert_eq!(Day11.part_a(CASE), 374.into());
+    }
+
+    #[test]
+    fn part_b() {
+        assert_eq!(Day11.part_b(CASE), 82000210.into());
+    }
+}

aoc_2023/src/lib.rs

@@ -12,6 +12,7 @@ mod day_07;
 mod day_08;
 mod day_09;
 mod day_10;
+mod day_11;
 // [import_marker]
 
 #[rustfmt::skip]
@@ -26,5 +27,6 @@ pub const ALL: &[&dyn Solution] = &[
     &day_08::Day08,
     &day_09::Day09,
     &day_10::Day10,
+    &day_11::Day11,
     // [list_marker]
 ];