Day 17 part 1.

src/day17.rs

@@ -0,0 +1,43 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+
+#[aoc_generator(day17)]
+fn parse(input: &str) -> Vec<u32> {
+    input.lines().map(|line| line.parse().unwrap()).collect()
+}
+
+#[aoc(day17, part1)]
+fn part1(input: &[u32]) -> usize {
+    bar(input, 150)
+}
+
+fn bar(containers: &[u32], target: u32) -> usize {
+    baz(containers, target, 0)
+}
+
+fn baz(containers: &[u32], target: u32, filled: u32) -> usize {
+    if filled > target {
+        return 0;
+    } else if filled == target {
+        return 1;
+    } else if containers.len() == 0 {
+        return 0;
+    }
+
+    baz(&containers[1..], target, filled + containers[0])
+        + baz(&containers[1..], target, filled)
+}
+
+#[aoc(day17, part2)]
+fn part2(_input: &[u32]) -> usize {
+    0
+}
+
+#[cfg(test)]
+mod test {
+    use crate::day17::bar;
+
+    #[test]
+    fn part1() {
+        assert_eq!(bar(&[20, 15, 10, 5, 5], 25), 4)
+    }
+}