2023 day16/rust: parallelize

2023/day16/rust/Cargo.toml

@@ -8,3 +8,4 @@ edition = "2021"
 [dependencies]
 aoc = { path = "../../../common/rust" }
 enum-map = "2.7.3"
+rayon = "1.8.0"

2023/day16/rust/src/main.rs

@@ -4,6 +4,7 @@ use std::{collections::HashMap, io::stdin};
 
 use aoc::vec2::{Direction, Vec2};
 use enum_map::EnumMap;
+use rayon::prelude::{IntoParallelIterator, ParallelIterator};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 enum Device {
@@ -168,9 +169,10 @@ fn main() {
             (Vec2::new(max_x - 1, y), Direction::Left),
         ]
     });
+    let starts: Vec<_> = hor_starts.chain(ver_starts).collect();
 
-    let max_energized = hor_starts
-        .chain(ver_starts)
+    let max_energized = starts
+        .into_par_iter()
         .map(|(pos, direction)| energize_fields(PathPosition { pos, direction }, fields.clone()))
         .max()
         .unwrap();

Cargo.lock

@@ -709,6 +709,7 @@ version = "0.1.0"
 dependencies = [
  "aoc",
  "enum-map",
+ "rayon",
 ]
 
 [[package]]