fun (unnecessary) parralel optimisations

JamesPatrickGill · Dec 8, 2024 · 88593b3 · 88593b3
1 parent e7d4a5f
commit 88593b3
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Showing 6 changed files with 95 additions and 35 deletions.
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
@@ -26,6 +26,7 @@ chrono = { version = "0.4.38", optional = true }
 dhat = { version = "0.3.3", optional = true }
 itertools = "0.13.0"
 pico-args = "0.5.0"
+rayon = "1.10.0"
 regex = "1.11.1"
 tinyjson = "2.5.1"
 

diff --git a/README.md b/README.md
@@ -29,9 +29,9 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 | [Day 3](./src/bin/03.rs) | `115.1µs` | `148.7µs` |
 | [Day 4](./src/bin/04.rs) | `81.9µs` | `51.3µs` |
 | [Day 5](./src/bin/05.rs) | `379.0µs` | `816.9µs` |
-| [Day 6](./src/bin/06.rs) | `331.5µs` | `311.0ms` |
-| [Day 7](./src/bin/07.rs) | `900.4µs` | `2.8ms` |
+| [Day 6](./src/bin/06.rs) | `358.0µs` | `31.5ms` |
+| [Day 7](./src/bin/07.rs) | `487.3µs` | `862.0µs` |
 | [Day 8](./src/bin/08.rs) | `36.5µs` | `116.8µs` |
 
-**Total: 317.20ms**
+**Total: 35.37ms**
 <!--- benchmarking table --->
diff --git a/src/bin/05.rs b/src/bin/05.rs
@@ -1,6 +1,6 @@
 use std::{
     cmp::Ordering,
-    collections::{HashMap, HashSet, VecDeque},
+    collections::{HashMap, HashSet},
 };
 
 use itertools::Itertools;

diff --git a/src/bin/06.rs b/src/bin/06.rs
@@ -1,5 +1,7 @@
 use std::collections::HashSet;
 
+use rayon::iter::{IntoParallelRefIterator, ParallelIterator};
+
 advent_of_code::solution!(6);
 
 #[derive(Debug, Eq, Hash, PartialEq, Clone, Copy)]
@@ -196,12 +198,15 @@ pub fn part_two(input: &str) -> Option<u32> {
         };
     }
 
-    let mut res = 0;
-    for block in potential_blocker_positions {
-        if check_for_loop(&rocks, x_max, y_max, block, start_guard) {
-            res += 1
-        };
-    }
+    let res = potential_blocker_positions
+        .par_iter()
+        .fold_with(0, |acc, block| {
+            if check_for_loop(&rocks, x_max, y_max, block, start_guard) {
+                return acc + 1;
+            };
+            acc
+        })
+        .sum();
 
     Some(res)
 }
@@ -236,12 +241,12 @@ fn check_for_loop(
     rocks: &HashSet<Pos>,
     x_max: i32,
     y_max: i32,
-    new_block: Pos,
+    new_block: &Pos,
     start_guard: Guard,
 ) -> bool {
     let mut guard = start_guard;
     let mut new_rocks = rocks.clone();
-    new_rocks.insert(new_block);
+    new_rocks.insert(new_block.to_owned());
 
     let mut visited = HashSet::new();
     loop {

diff --git a/src/bin/07.rs b/src/bin/07.rs
@@ -2,6 +2,8 @@ use std::collections::HashSet;
 
 use itertools::Itertools;
 
+use rayon::iter::{IntoParallelRefIterator, ParallelIterator};
+
 advent_of_code::solution!(7);
 
 #[derive(Debug, Eq, Hash, PartialEq, Clone)]
@@ -26,13 +28,16 @@ pub fn part_one(input: &str) -> Option<i64> {
         })
         .collect_vec();
 
-    let result: i64 = equations.into_iter().fold(0, |acc, eq| {
-        if solve_equation(&eq).is_some() {
-            acc + eq.target
-        } else {
-            acc
-        }
-    });
+    let result: i64 = equations
+        .par_iter()
+        .fold_with(0, |acc, eq| {
+            if solve_equation(eq).is_some() {
+                acc + eq.target
+            } else {
+                acc
+            }
+        })
+        .sum();
 
     Some(result)
 }
@@ -41,11 +46,11 @@ fn solve_equation(equation: &Equation) -> Option<HashSet<Vec<char>>> {
     let mut solutions = HashSet::new();
     if equation.numbers.len() == 2 {
         if equation.numbers[0] + equation.numbers[1] == equation.target {
-            solutions.insert(vec!['+'].into());
+            solutions.insert(vec!['+']);
         };
 
         if equation.numbers[0] * equation.numbers[1] == equation.target {
-            solutions.insert(vec!['*'].into());
+            solutions.insert(vec!['*']);
         };
 
         return if solutions.is_empty() {
@@ -113,33 +118,36 @@ pub fn part_two(input: &str) -> Option<i64> {
         })
         .collect_vec();
 
-    let result: i64 = equations.into_iter().fold(0, |acc, eq| {
-        if solve_equation_2(&eq).is_some() {
-            acc + eq.target
-        } else {
-            acc
-        }
-    });
+    let result: i64 = equations
+        .par_iter()
+        .fold_with(0, |acc, eq| {
+            if solve_equation_2(eq).is_some() {
+                acc + eq.target
+            } else {
+                acc
+            }
+        })
+        .sum();
 
     Some(result)
 }
 
-fn solve_equation_2(equation: &Equation) -> Option<HashSet<VecDeque<char>>> {
+fn solve_equation_2(equation: &Equation) -> Option<HashSet<Vec<char>>> {
     let mut solutions = HashSet::new();
     if equation.numbers.len() == 2 {
         if equation.numbers[0] + equation.numbers[1] == equation.target {
-            solutions.insert(vec!['+'].into());
+            solutions.insert(vec!['+']);
         };
 
         if equation.numbers[0] * equation.numbers[1] == equation.target {
-            solutions.insert(vec!['*'].into());
+            solutions.insert(vec!['*']);
         };
 
         let concat = format!("{}{}", equation.numbers[0], equation.numbers[1])
             .parse::<i64>()
             .unwrap();
         if concat == equation.target {
-            solutions.insert(vec!['|'].into());
+            solutions.insert(vec!['|']);
         };
 
         return if solutions.is_empty() {
@@ -162,7 +170,7 @@ fn solve_equation_2(equation: &Equation) -> Option<HashSet<VecDeque<char>>> {
         if let Some(sols) = add_smaller_solutions {
             for sol in sols {
                 let mut new_sol = sol.clone();
-                new_sol.push_back('+');
+                new_sol.push('+');
                 solutions.insert(new_sol);
             }
         }
@@ -178,7 +186,7 @@ fn solve_equation_2(equation: &Equation) -> Option<HashSet<VecDeque<char>>> {
         if let Some(sols) = mult_smaller_solutions {
             for sol in sols {
                 let mut new_sol = sol.clone();
-                new_sol.push_back('*');
+                new_sol.push('*');
                 solutions.insert(new_sol);
             }
         };
@@ -196,7 +204,7 @@ fn solve_equation_2(equation: &Equation) -> Option<HashSet<VecDeque<char>>> {
             if let Some(sols) = concat_smaller_solutions {
                 for sol in sols {
                     let mut new_sol = sol.clone();
-                    new_sol.push_back('|');
+                    new_sol.push('|');
                     solutions.insert(new_sol);
                 }
             };