hmm

Cargo.lock

@@ -23,6 +23,7 @@ dependencies = [
 name = "aoc2023"
 version = "0.1.0"
 dependencies = [
+ "itertools",
  "regex",
  "shared",
  "substring",
@@ -34,6 +35,21 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
+[[package]]
+name = "either"
+version = "1.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a26ae43d7bcc3b814de94796a5e736d4029efb0ee900c12e2d54c993ad1a1e07"
+
+[[package]]
+name = "itertools"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "25db6b064527c5d482d0423354fcd07a89a2dfe07b67892e62411946db7f07b0"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "memchr"
 version = "2.6.4"

aoc2023/Cargo.toml

@@ -6,4 +6,5 @@ edition = "2021"
 [dependencies]
 shared = { path = "../shared" }
 regex = "1.10.2"
-substring = "1.4.5"
+substring = "1.4.5"
+itertools = "0.12.0"

aoc2023/src/day11.rs

@@ -1,13 +1,55 @@
 use shared::{Solution, Answer};
+use itertools::Itertools;
 
 pub struct Day11;
 
 impl Solution for Day11 {
     fn part_1(&self, input: &str) -> Answer {
-        Answer::Unimplemented
+        Answer::from(solve(input, 2))
     }
 
     fn part_2(&self, input: &str) -> Answer {
-        Answer::Unimplemented
+        Answer::from(solve(input, 1_000_000))
     }
 }
+
+fn solve(input: &str, inflation_arg: usize) -> u64 {
+    let grid = input.lines().map(|line| line.chars().map(|x| x == '#').collect::<Vec<bool>>()).collect::<Vec<_>>();
+
+    let mut distances = vec![vec![1; grid[0].len()]; grid.len()];
+
+    let mut empty_col = vec![true; grid[0].len()];
+    for (i, line) in grid.iter().enumerate() {
+        empty_col = empty_col.iter().enumerate().map(|(i, &l)| l && !line[i]).collect();
+        if !line.iter().any(|&x| x) {
+            distances[i] = vec![inflation_arg; line.len()];
+        }
+    }
+
+    for (i, &col) in empty_col.iter().enumerate() {
+        if col {
+            for j in 0..distances.len() {
+                distances[j][i] = inflation_arg;
+            }
+        }
+    }
+
+    let galaxies: Vec<(usize, usize)> = grid.iter().
+        enumerate().
+        map(|(i, line)| line.iter()
+            .enumerate()
+            .filter_map(|(j, &x)| if x { Some((i, j)) } else { None })
+            .collect::<Vec<_>>()
+        ).flatten().collect::<Vec<_>>();
+
+    galaxies.iter().permutations(2).map(|x| {
+        let (x1, y1): (usize, usize) = *x[0];
+        let (x2, y2): (usize, usize) = *x[1];
+        let mut out = 0;
+        let xrange = x1.min(x2)..x1.max(x2);
+        let yrange = if y1 <= y2 { y1..y2 } else { (y2+1)..(y1+1) };
+        for i in xrange { out += distances[i][if x1 <= x2 {y1} else {y2}] }
+        for j in yrange { out += distances[x1.min(x2)][j] }
+        out as u64
+    } ).sum::<u64>() / 2
+}

src/main.rs

@@ -8,10 +8,10 @@ use std::time::Instant;
 fn main() {
     let now = Instant::now();
 
-    let Ok(data) = load_actual(2023, 10)
+    let Ok(data) = load_actual(2023, 11)
         else { panic!("No Input Data"); };
 
-    let result = aoc2023::day10::Day10.part_2(&data);
+    let result = aoc2023::day11::Day11.part_2(&data);
 
     let elapsed = now.elapsed();