day17

3 files changed, 70 insertions, 0 deletions

diff --git a/inputs/day17 b/inputs/day17
new file mode 100644
index 0000000..6b25a72
--- /dev/null
+++ b/inputs/day17
@@ -0,0 +1,20 @@
+33
+14
+18
+20
+45
+35
+16
+35
+1
+13
+18
+13
+50
+44
+48
+6
+24
+41
+30
+42
diff --git a/src/bin/day17.rs b/src/bin/day17.rs
new file mode 100644
index 0000000..1f3d009
--- /dev/null
+++ b/src/bin/day17.rs
@@ -0,0 +1,41 @@
+use itertools::Itertools;
+
+fn main() {
+    let input = advent::read_numbers(17);
+    println!("17a: {}", container_fittings(&input, 150));
+    println!("17b: {}", minimum_containers(&input, 150));
+}
+
+fn container_fittings(input: &[u16], target: u16) -> usize {
+    input.iter()
+         .powerset()
+         .filter(|containers| containers.iter().copied().sum::<u16>() == target)
+         .count()
+}
+
+fn minimum_containers(input: &[u16], target: u16) -> usize {
+    let min_count = input.iter()
+                         .powerset()
+                         .filter(|containers| containers.iter().copied().sum::<u16>() == target)
+                         .map(|containers| containers.len())
+                         .min()
+                         .unwrap();
+
+    input.iter()
+         .powerset()
+         .filter(|containers| containers.len() == min_count)
+         .filter(|containers| containers.iter().copied().sum::<u16>() == target)
+         .count()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let input = [20, 15, 10, 5, 5];
+        assert_eq!(container_fittings(&input, 25), 4);
+        assert_eq!(minimum_containers(&input, 25), 3);
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 501b2f7..f0199c7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,6 @@
+use std::str::FromStr;
+use std::fmt::Debug;
+
 pub fn read_file(day: u8) -> String {
     let filename = format!("inputs/day{}", day);
     std::fs::read_to_string(filename).unwrap()
@@ -8,3 +11,9 @@ pub fn read_lines(day: u8) -> Vec<String> {
                   .map(String::from)
                   .collect()
 }
+
+pub fn read_numbers<T: FromStr>(day: u8) -> Vec<T> where <T as FromStr>::Err: Debug {
+    read_lines(day).iter()
+                   .map(|n| n.parse::<T>().unwrap())
+                   .collect::<Vec<T>>()
+}