From bb03ac3dca346bb50e54ba55964fde975a6218eb Mon Sep 17 00:00:00 2001
From: Dominic <git@msrd0.de>
Date: Mon, 11 Dec 2023 11:13:02 +0100
Subject: [PATCH] day 11 part 2

---
 src/bin/day11.rs | 66 ++++++++++++++++++++++++++++++------------------
 1 file changed, 41 insertions(+), 25 deletions(-)

diff --git a/src/bin/day11.rs b/src/bin/day11.rs
index 4b4da3b..e272b54 100644
--- a/src/bin/day11.rs
+++ b/src/bin/day11.rs
@@ -27,6 +27,39 @@ fn parser() -> impl Parser<char, Vec<Vec<Cell>>, Error = Simple<char>> {
 		.then_ignore(end())
 }
 
+fn sum_shortest_paths(
+	empty_rows: &HashSet<usize>,
+	empty_cols: &HashSet<usize>,
+	galaxies: &[(usize, usize)],
+	multiplier: u64
+) -> u64 {
+	let mut sum = 0;
+	for (i, g) in galaxies.iter().enumerate() {
+		for (_j, h) in galaxies.iter().enumerate().skip(i + 1) {
+			let mut x = [g.0, h.0];
+			x.sort_unstable();
+			let mut dist = (x[0] .. x[1])
+				.map(|row| match empty_rows.contains(&row) {
+					true => multiplier,
+					false => 1
+				})
+				.sum::<u64>();
+
+			let mut y = [g.1, h.1];
+			y.sort_unstable();
+			dist += (y[0] .. y[1])
+				.map(|col| match empty_cols.contains(&col) {
+					true => multiplier,
+					false => 1
+				})
+				.sum::<u64>();
+			// eprintln!(" - Between galaxy {} and galaxy {}: {dist}", i + 1, _j + 1);
+			sum += dist;
+		}
+	}
+	sum
+}
+
 fn main() -> anyhow::Result<()> {
 	let universe = read("inputs/day11.txt", parser())?;
 
@@ -53,31 +86,14 @@ fn main() -> anyhow::Result<()> {
 		.map(|(i, j, _)| (i, j))
 		.collect();
 
-	let mut sum = 0_u64;
-	for (i, g) in galaxies.iter().enumerate() {
-		for (_j, h) in galaxies.iter().enumerate().skip(i + 1) {
-			let mut x = [g.0, h.0];
-			x.sort_unstable();
-			let mut dist = (x[0] .. x[1])
-				.map(|row| match empty_rows.contains(&row) {
-					true => 2,
-					false => 1
-				})
-				.sum::<u64>();
-
-			let mut y = [g.1, h.1];
-			y.sort_unstable();
-			dist += (y[0] .. y[1])
-				.map(|col| match empty_cols.contains(&col) {
-					true => 2,
-					false => 1
-				})
-				.sum::<u64>();
-			// eprintln!(" - Between galaxy {} and galaxy {}: {dist}", i + 1, _j + 1);
-			sum += dist;
-		}
-	}
-	println!("{sum}");
+	println!(
+		"{}",
+		sum_shortest_paths(&empty_rows, &empty_cols, &galaxies, 2)
+	);
+	println!(
+		"{}",
+		sum_shortest_paths(&empty_rows, &empty_cols, &galaxies, 1_000_000)
+	);
 
 	Ok(())
 }