3 files changed, 100 insertions, 0 deletions
diff --git a/2024/05/rust/Cargo.lock b/2024/05/rust/Cargo.lock
new file mode 100644
index 0000000..5ae963b
--- /dev/null
+++ b/2024/05/rust/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "aoc_2024-05"
+version = "0.1.0"
diff --git a/2024/05/rust/Cargo.toml b/2024/05/rust/Cargo.toml
new file mode 100644
index 0000000..de0fa13
--- /dev/null
+++ b/2024/05/rust/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "aoc_2024-05"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
diff --git a/2024/05/rust/src/main.rs b/2024/05/rust/src/main.rs
new file mode 100644
index 0000000..bf72727
--- /dev/null
+++ b/2024/05/rust/src/main.rs
@@ -0,0 +1,87 @@
+#![feature(slice_split_once)]
+
+use std::cmp::Ordering;
+use std::collections::HashMap;
+use std::io;
+
+fn main() -> io::Result<()> {
+    let lines = io::stdin().lines().flatten().collect::<Vec<_>>();
+    let (rules, updates) = lines.split_once(String::is_empty).unwrap();
+    let manual = rules.iter().collect::<Manual>();
+
+    let updates = updates
+        .iter()
+        .map(|up| {
+            up.split(',')
+                .map(|p| Page {
+                    number: p.parse::<u64>().unwrap(),
+                    manual: &manual,
+                })
+                .collect::<_>()
+        })
+        .collect::<Vec<Vec<_>>>();
+
+    let mut silver = 0;
+    let mut gold = 0;
+    for mut up in updates {
+        let mid = up.len() / 2;
+        if up.is_sorted() {
+            silver += up[mid].number;
+        } else {
+            up.sort_unstable();
+            gold += up[mid].number;
+        }
+    }
+
+    println!("silver: {silver}");
+    println!("gold: {gold}");
+
+    return Ok(());
+}
+#[derive(Debug)]
+struct Manual {
+    order: HashMap<u64, Vec<u64>>,
+}
+
+impl<'a> FromIterator<&'a String> for Manual {
+    fn from_iter<T: IntoIterator<Item = &'a String>>(rules: T) -> Self {
+        let mut order = HashMap::<u64, Vec<u64>>::new();
+        for rule in rules {
+            let (pre, post) = rule.split_once('|').unwrap();
+            order
+                .entry(pre.parse().unwrap())
+                .or_default()
+                .push(post.parse().unwrap());
+        }
+        Manual { order }
+    }
+}
+
+#[derive(Clone, Copy)]
+struct Page<'a> {
+    number: u64,
+    manual: &'a Manual,
+}
+
+impl PartialEq for Page<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.number == other.number
+    }
+}
+impl Eq for Page<'_> {}
+
+impl PartialOrd for Page<'_> {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        if self.manual.order.get(&self.number)?.contains(&other.number) {
+            Some(Ordering::Less)
+        } else {
+            Some(Ordering::Greater)
+        }
+    }
+}
+
+impl Ord for Page<'_> {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.partial_cmp(other).unwrap()
+    }
+}