From b45852b9347cbb77870df9c81369b8f82bfd542e Mon Sep 17 00:00:00 2001
From: Johannes <freelon@gmx.net>
Date: Sat, 13 Jan 2024 19:42:53 +0100
Subject: [PATCH] Day 13 part 2.

---
 src/day13.rs | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/src/day13.rs b/src/day13.rs
index c4e777a..2310b74 100644
--- a/src/day13.rs
+++ b/src/day13.rs
@@ -23,10 +23,9 @@ fn part1(deltas: &HashMap<(String, String), i32>) -> i32 {
     permutations(names).iter().map(|arrangement| {
         let mut happiness = 0;
         for i in 0..arrangement.len() {
-            let left = if i == 0 { arrangement.len() - 1 } else { i - 1 };
             let right = (i + 1) % arrangement.len();
-            happiness += deltas[&(arrangement[left].clone(), arrangement[i].clone())] +
-                deltas[&(arrangement[i].clone(), arrangement[left].clone())];
+            happiness += deltas[&(arrangement[right].clone(), arrangement[i].clone())] +
+                deltas[&(arrangement[i].clone(), arrangement[right].clone())];
         }
         happiness
     }).max().unwrap()
@@ -54,10 +53,20 @@ fn p(mut input: Vec<String>) -> Vec<Vec<String>> {
 }
 
 
-// #[aoc(day13, part2)]
-// fn part2(input: &str) -> String {
-//     todo!()
-// }
+#[aoc(day13, part2)]
+fn part2(deltas: &HashMap<(String, String), i32>) -> i32 {
+    let mut names: HashSet<_> = deltas.keys().map(|s| s.0.clone()).collect();
+    names.insert("me".to_string());
+    permutations(names).iter().map(|arrangement| {
+        let mut happiness = 0;
+        for i in 0..arrangement.len() {
+            let right = (i + 1) % arrangement.len();
+            happiness += deltas.get(&(arrangement[right].clone(), arrangement[i].clone())).or(Some(&0)).unwrap() +
+                deltas.get(&(arrangement[i].clone(), arrangement[right].clone())).or(Some(&0)).unwrap();
+        }
+        happiness
+    }).max().unwrap()
+}
 
 #[cfg(test)]
 mod test {