2023 day11/rust: add solution

2023/day11/rust/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "rust_2023_11"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+aoc = { path = "../../../common/rust" }
+itertools = "0.12.0"

2023/day11/rust/src/main.rs

@@ -0,0 +1,56 @@
+#![warn(clippy::pedantic)]
+
+use std::io::stdin;
+
+use itertools::Itertools;
+
+fn expand(galaxies: &[(usize, usize)], factor: usize) -> impl Iterator<Item = (usize, usize)> + '_ {
+    fn find_holes<I>(it: &I) -> Vec<usize>
+    where
+        I: Iterator<Item = usize> + Clone,
+    {
+        (0..it.clone().max().unwrap())
+            .filter(|n| !it.clone().contains(n))
+            .collect()
+    }
+
+    let empty_rows = find_holes(&galaxies.iter().map(|&(row, _col)| row));
+    let empty_cols = find_holes(&galaxies.iter().map(|&(_row, col)| col));
+
+    galaxies.iter().map(move |&(x, y)| {
+        let additional_rows = empty_rows.iter().filter(|&&row| row < x).count() * (factor - 1);
+        let additional_cols = empty_cols.iter().filter(|&&col| col < y).count() * (factor - 1);
+
+        (x + additional_rows, y + additional_cols)
+    })
+}
+
+fn distances_sum<I: IntoIterator<Item = (usize, usize)>>(galaxies: I) -> usize {
+    galaxies
+        .into_iter()
+        .combinations(2)
+        .map(|pos| {
+            let &[(x1, y1), (x2, y2)] = pos.as_slice() else {
+                panic!()
+            };
+            x1.abs_diff(x2) + y1.abs_diff(y2)
+        })
+        .sum()
+}
+
+fn main() {
+    let galaxies: Vec<_> = stdin()
+        .lines()
+        .map(Result::unwrap)
+        .enumerate()
+        .flat_map(|(row, l)| {
+            l.into_bytes()
+                .into_iter()
+                .enumerate()
+                .filter_map(move |(col, c)| (c == b'#').then_some((row, col)))
+        })
+        .collect();
+
+    println!("{}", distances_sum(expand(&galaxies, 2)));
+    println!("{}", distances_sum(expand(&galaxies, 1_000_000)));
+}

Cargo.lock

@@ -687,6 +687,14 @@ dependencies = [
  "itertools 0.12.0",
 ]
 
+[[package]]
+name = "rust_2023_11"
+version = "0.1.0"
+dependencies = [
+ "aoc",
+ "itertools 0.12.0",
+]
+
 [[package]]
 name = "rustversion"
 version = "1.0.14"

Cargo.toml

@@ -35,4 +35,5 @@ members = [
 	"2023/day7/rust",
 	"2023/day8/rust",
 	"2023/day9/rust",
+	"2023/day11/rust",
 ]