Speed up day5

day5/Cargo.lock

@@ -2,6 +2,60 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "613f8cc01fe9cf1a3eb3d7f488fd2fa8388403e97039e2f73692932e291a770d"
+dependencies = [
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b82ac4a3c2ca9c3460964f020e1402edd5753411d7737aa39c3714ad1b5420e"
+dependencies = [
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "22ec99545bb0ed0ea7bb9b8e1e9122ea386ff8a48c0922e43f36d45ab09e0e80"
+
 [[package]]
 name = "day5"
 version = "0.1.0"
+dependencies = [
+ "rayon",
+]
+
+[[package]]
+name = "either"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
+
+[[package]]
+name = "rayon"
+version = "1.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b418a60154510ca1a002a752ca9714984e21e4241e804d32555251faf8b78ffa"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1465873a3dfdaa8ae7cb14b4383657caab0b3e8a0aa9ae8e04b044854c8dfce2"
+dependencies = [
+ "crossbeam-deque",
+ "crossbeam-utils",
+]

day5/Cargo.toml

@@ -4,3 +4,4 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+rayon = "1.10.0"

day5/src/main.rs

@@ -1,3 +1,5 @@
+use rayon::prelude::*;
+
 struct ParsedInput {
     rules: Vec<(u32, u32)>,
     pages: Vec<Vec<u32>>,
@@ -33,35 +35,33 @@ fn all_rules_apply(rules: &[(u32, u32)], page: &[u32]) -> bool {
 fn part1(parsed_input: &ParsedInput) -> u32 {
     parsed_input
         .pages
-        .iter()
+        .par_iter()
         .filter(|page| all_rules_apply(&parsed_input.rules, page))
         .map(|rule| rule[rule.len() / 2])
         .sum()
 }
 
-fn part2(parsed_input: &ParsedInput) -> u32 {
-    parsed_input
-        .pages
-        .iter()
-        .filter(|page| !all_rules_apply(&parsed_input.rules, page))
-        .fold(vec![], |mut acc, curr| {
-            let mut corrected_page = curr.clone();
-            corrected_page.sort_unstable_by(|a, b| {
-                match all_rules_apply(&parsed_input.rules, &[*a, *b]) {
+fn correct_page(page: &mut [u32], rules: &[(u32, u32)]) {
+    page.sort_by(|a, b| match all_rules_apply(rules, &[*a, *b]) {
         true => std::cmp::Ordering::Less,
         false => std::cmp::Ordering::Greater,
-                }
     });
-            acc.push(corrected_page);
-            acc
+}
+
+fn part2(parsed_input: &mut ParsedInput) -> u32 {
+    parsed_input
+        .pages
+        .par_iter_mut()
+        .filter(|page| !all_rules_apply(&parsed_input.rules, page))
+        .map(|page| {
+            correct_page(page, &parsed_input.rules);
+            page[page.len() / 2]
         })
-        .iter()
-        .map(|rule| rule[rule.len() / 2])
         .sum()
 }
 
 fn main() {
-    let input = parse(include_str!("../input.txt"));
+    let mut input = parse(include_str!("../input.txt"));
     println!("{}", part1(&input));
-    println!("{}", part2(&input));
+    println!("{}", part2(&mut input));
 }