solution: day24

src/bin/24.rs

@@ -0,0 +1,44 @@
+use aoc::helpers::to_vec;
+use itertools::Itertools;
+
+fn balance(gifts: &[u64], parts: u64) -> Option<u64> {
+    let part = gifts.iter().sum::<u64>() / parts;
+
+    // greedily search for smallest
+    for i in 1..gifts.len() {
+        for comb in gifts.iter().combinations(i) {
+            if comb.iter().copied().sum::<u64>() == part {
+                return Some(comb.iter().copied().product());
+            }
+        }
+    }
+    None
+}
+
+pub fn part_one(input: &str) -> Option<u64> {
+    let gifts = to_vec(input, '\n');
+    balance(&gifts, 3)
+}
+pub fn part_two(input: &str) -> Option<u64> {
+    let gifts = to_vec(input, '\n');
+    balance(&gifts, 4)
+}
+fn main() {
+    let input = &aoc::read_file("inputs", 24);
+    aoc::solve!(1, part_one, input);
+    aoc::solve!(2, part_two, input);
+}
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        let input = aoc::read_file("test_inputs", 24);
+        assert_eq!(part_one(&input.trim()), Some(99));
+    }
+    #[test]
+    fn test_part_two() {
+        let input = aoc::read_file("test_inputs", 24);
+        assert_eq!(part_two(&input.trim()), Some(44));
+    }
+}

src/test_inputs/24.txt

@@ -0,0 +1,10 @@
+1
+2
+3
+4
+5
+7
+8
+9
+10
+11