more correct is a random shuffling of the vertices, otherwise an evil…

… input could make us go slow

Cargo.toml

@@ -37,3 +37,4 @@ tinyvec = "1.6.0"
 fxhash = "0.2.1"
 ndarray = "0.15.6"
 ndarray-linalg = { version = "0.16.0", features = ["openblas-static"] }
+rand = "0.8.5"

README.md

@@ -65,9 +65,9 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 | [Day 22](./src/bin/22.rs) | `78.3µs` | `194.8µs` |
 | [Day 23](./src/bin/23.rs) | `330.4µs` | `13.3ms` |
 | [Day 24](./src/bin/24.rs) | `257.2µs` | `16.2µs` |
-| [Day 25](./src/bin/25.rs) | `239.4µs` | `-` |
+| [Day 25](./src/bin/25.rs) | `256.4µs` | `-` |
 
-**Total: 30.75ms**
+**Total: 30.77ms**
 <!--- benchmarking table --->
 
 ---

src/bin/25.rs

@@ -1,13 +1,18 @@
 use std::collections::VecDeque;
 
 use fxhash::FxHashMap;
+use rand::{seq::SliceRandom, thread_rng};
 
 advent_of_code::solution!(25, 1);
 
 pub fn part_one(input: &str) -> Option<usize> {
     let mut flow: NetworkFlow = parse_graph(input).into();
     let s = 0;
-    (1..flow.vertices).find_map(|t| find_cut_of_size(&mut flow, s, t, 3))
+    let mut vertices = (1..flow.vertices).collect::<Vec<_>>();
+    vertices.shuffle(&mut thread_rng());
+    vertices
+        .into_iter()
+        .find_map(|t| find_cut_of_size(&mut flow, s, t, 3))
 }
 
 fn find_cut_of_size(net: &mut NetworkFlow, s: usize, t: usize, cut: i16) -> Option<usize> {