From 18effe21f371a709926577de795b696ad1476c40 Mon Sep 17 00:00:00 2001
From: Kevin Caffrey <kcaffrey@gmail.com>
Date: Tue, 26 Dec 2023 10:29:13 -0500
Subject: [PATCH] more correct is a random shuffling of the vertices, otherwise
 an evil input could make us go slow

---
 Cargo.lock    | 1 +
 Cargo.toml    | 1 +
 README.md     | 4 ++--
 src/bin/25.rs | 7 ++++++-
 4 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 6da62b0..04e4434 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -31,6 +31,7 @@ dependencies = [
  "ndarray-linalg",
  "num-integer",
  "pico-args",
+ "rand",
  "rayon",
  "smallvec",
  "thiserror",
diff --git a/Cargo.toml b/Cargo.toml
index 94aa64b..c2512d3 100644
--- a/Cargo.toml
+++ b/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"
diff --git a/README.md b/README.md
index 3e07e98..f93da2b 100644
--- a/README.md
+++ b/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 --->
 
 ---
diff --git a/src/bin/25.rs b/src/bin/25.rs
index f5c8948..145f3b6 100644
--- a/src/bin/25.rs
+++ b/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> {