From 95acefb1284579d640db6f8b0c11a2531312d108 Mon Sep 17 00:00:00 2001
From: timeshifter <timeshifter@sumatrae>
Date: Sun, 5 Jul 2026 19:41:49 +0200
Subject: [PATCH] add day 24

---
 day24/Cargo.lock  |  25 ++++++++
 day24/Cargo.toml  |   7 +++
 day24/example.txt |  10 ++++
 day24/input.txt   |  28 +++++++++
 day24/src/main.rs | 142 ++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 212 insertions(+)
 create mode 100644 day24/Cargo.lock
 create mode 100644 day24/Cargo.toml
 create mode 100644 day24/example.txt
 create mode 100644 day24/input.txt
 create mode 100644 day24/src/main.rs

diff --git a/day24/Cargo.lock b/day24/Cargo.lock
new file mode 100644
index 0000000..45a4ac0
--- /dev/null
+++ b/day24/Cargo.lock
@@ -0,0 +1,25 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day24"
+version = "0.1.0"
+dependencies = [
+ "itertools",
+]
+
+[[package]]
+name = "either"
+version = "1.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "91622ff5e7162018101f2fea40d6ebf4a78bbe5a49736a2020649edf9693679e"
+
+[[package]]
+name = "itertools"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b4baf93f58d4425749ca49a51c50ebab072c5df6994d08fed93541c331481dc"
+dependencies = [
+ "either",
+]
diff --git a/day24/Cargo.toml b/day24/Cargo.toml
new file mode 100644
index 0000000..58dd58f
--- /dev/null
+++ b/day24/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "day24"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+itertools = "*"
diff --git a/day24/example.txt b/day24/example.txt
new file mode 100644
index 0000000..f4909b4
--- /dev/null
+++ b/day24/example.txt
@@ -0,0 +1,10 @@
+1
+2
+3
+4
+5
+7
+8
+9
+10
+11
diff --git a/day24/input.txt b/day24/input.txt
new file mode 100644
index 0000000..874e61e
--- /dev/null
+++ b/day24/input.txt
@@ -0,0 +1,28 @@
+1
+3
+5
+11
+13
+17
+19
+23
+29
+31
+41
+43
+47
+53
+59
+61
+67
+71
+73
+79
+83
+89
+97
+101
+103
+107
+109
+113
diff --git a/day24/src/main.rs b/day24/src/main.rs
new file mode 100644
index 0000000..622cef3
--- /dev/null
+++ b/day24/src/main.rs
@@ -0,0 +1,142 @@
+use itertools::Itertools;
+
+#[cfg(debug_assertions)]
+const INPUT: &str = "example.txt";
+#[cfg(debug_assertions)]
+const LENGTH: usize = 10;
+
+#[cfg(not(debug_assertions))]
+const INPUT: &str = "input.txt";
+#[cfg(not(debug_assertions))]
+const LENGTH: usize = 28;
+
+fn main() {
+    let packages: Vec<u64> = std::fs::read_to_string(INPUT)
+        .unwrap()
+        .lines()
+        .map(|l| l.parse().unwrap())
+        .collect();
+
+    part_1(packages.clone());
+    part_2(packages)
+}
+
+fn part_2(packages: Vec<u64>) {
+    let total_weight = packages.iter().sum::<u64>();
+
+    let target_weight = total_weight / 4;
+
+    let best_qe = u64::MAX;
+
+    let lowest_center_count = 1000;
+
+    'outer: for kc in 1..LENGTH - 3 {
+        if lowest_center_count < kc {
+            break 'outer;
+        }
+        for mut center in packages.iter().combinations(kc) {
+            if weight(&center) != target_weight {
+                continue;
+            }
+
+            let mut remaining_packages = packages.clone();
+            remaining_packages.sort();
+
+            center.sort();
+
+            let mut to_remove = vec![];
+
+            let qe = product(&center);
+
+            for (idx, rem_package) in remaining_packages.iter().enumerate() {
+                if center.contains(&rem_package) {
+                    to_remove.push(idx)
+                }
+            }
+
+            for idx in to_remove.into_iter().rev() {
+                remaining_packages.remove(idx);
+            }
+
+            for kl in 1..LENGTH - kc - 2 {
+                for left in remaining_packages.iter().combinations(kl) {
+                    if weight(&left) != target_weight {
+                        continue;
+                    }
+
+                    if qe < best_qe && center.len() <= lowest_center_count {
+                        println!("{}", qe);
+                        break 'outer;
+                    }
+                }
+            }
+        }
+    }
+}
+
+fn part_1(packages: Vec<u64>) {
+    let total_weight = packages.iter().sum::<u64>();
+
+    let target_weight = total_weight / 3;
+
+    let best_qe = u64::MAX;
+
+    let lowest_center_count = 1000;
+
+    'outer: for kc in 1..LENGTH - 2 {
+        if lowest_center_count < kc {
+            break 'outer;
+        }
+        for mut center in packages.iter().combinations(kc) {
+            if weight(&center) != target_weight {
+                continue;
+            }
+
+            let mut remaining_packages = packages.clone();
+            remaining_packages.sort();
+
+            center.sort();
+
+            let mut to_remove = vec![];
+
+            let qe = product(&center);
+
+            for (idx, rem_package) in remaining_packages.iter().enumerate() {
+                if center.contains(&rem_package) {
+                    to_remove.push(idx)
+                }
+            }
+
+            for idx in to_remove.into_iter().rev() {
+                remaining_packages.remove(idx);
+            }
+
+            for kl in 1..LENGTH - kc - 1 {
+                for left in remaining_packages.iter().combinations(kl) {
+                    if weight(&left) != target_weight {
+                        continue;
+                    }
+
+                    if qe < best_qe && center.len() <= lowest_center_count {
+                        println!("{}", qe);
+                        break 'outer;
+                    }
+                }
+            }
+        }
+    }
+}
+
+fn weight<'a, T>(slice: &'a [&'a T]) -> T
+where
+    T: std::iter::Sum<&'a T>,
+{
+    slice.iter().copied().sum::<T>()
+}
+
+fn product<'a, T>(slice: &'a [&'a T]) -> T
+where
+    T: std::iter::Product<&'a T>,
+{
+    slice.iter().copied().product::<T>()
+}