day 20

2 files changed, 76 insertions, 0 deletions

diff --git a/src/bin/2022/day20.rs b/src/bin/2022/day20.rs
new file mode 100644
index 0000000..654ea60
--- /dev/null
+++ b/src/bin/2022/day20.rs
@@ -0,0 +1,74 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+
+use advent_of_code::prelude::*;
+
+#[derive(Default)]
+pub struct WrappingQueue {
+    queue: Vec<(usize, isize)>,
+}
+
+impl std::fmt::Debug for WrappingQueue {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_list()
+            .entries(self.queue.iter().copied().map(|v| v.1))
+            .finish()
+    }
+}
+
+impl WrappingQueue {
+    fn mix(&mut self, idx: usize) {
+        let val = self.queue.remove(idx);
+        let new_idx: usize = ((idx as isize + val.1)
+            .rem_euclid(self.queue.len() as isize))
+        .try_into()
+        .unwrap();
+        self.queue.insert(new_idx, val);
+    }
+}
+
+pub fn parse(fh: File) -> Result<WrappingQueue> {
+    Ok(WrappingQueue {
+        queue: parse::lines(fh).enumerate().collect(),
+    })
+}
+
+pub fn part1(mut q: WrappingQueue) -> Result<isize> {
+    for i in 0..q.queue.len() {
+        let idx = q.queue.iter().position(|(idx, _)| *idx == i).unwrap();
+        q.mix(idx);
+    }
+    let zero_idx = q.queue.iter().position(|(_, val)| *val == 0).unwrap();
+    Ok(q.queue[(zero_idx + 1000) % q.queue.len()].1
+        + q.queue[(zero_idx + 2000) % q.queue.len()].1
+        + q.queue[(zero_idx + 3000) % q.queue.len()].1)
+}
+
+pub fn part2(q: WrappingQueue) -> Result<isize> {
+    let key = 811589153;
+    let mut q = WrappingQueue {
+        queue: q.queue.into_iter().map(|(i, v)| (i, key * v)).collect(),
+    };
+    for _ in 0..10 {
+        for i in 0..q.queue.len() {
+            let idx = q.queue.iter().position(|(idx, _)| *idx == i).unwrap();
+            q.mix(idx);
+        }
+    }
+    let zero_idx = q.queue.iter().position(|(_, val)| *val == 0).unwrap();
+    Ok(q.queue[(zero_idx + 1000) % q.queue.len()].1
+        + q.queue[(zero_idx + 2000) % q.queue.len()].1
+        + q.queue[(zero_idx + 3000) % q.queue.len()].1)
+}
+
+#[test]
+fn test() {
+    assert_eq!(
+        part1(parse(parse::data(2022, 20).unwrap()).unwrap()).unwrap(),
+        17490
+    );
+    assert_eq!(
+        part2(parse(parse::data(2022, 20).unwrap()).unwrap()).unwrap(),
+        1632917375836
+    );
+}
diff --git a/src/bin/2022/main.rs b/src/bin/2022/main.rs
index 2aa8500..d13e807 100644
--- a/src/bin/2022/main.rs
+++ b/src/bin/2022/main.rs
@@ -30,6 +30,7 @@ mod day16;
 mod day17;
 mod day18;
 mod day19;
+mod day20;
 // NEXT MOD
 
 #[paw::main]
@@ -55,6 +56,7 @@ fn main(opt: Opt) -> Result<()> {
         17 => advent_of_code::day!(2022, opt.day, opt.puzzle, day17),
         18 => advent_of_code::day!(2022, opt.day, opt.puzzle, day18),
         19 => advent_of_code::day!(2022, opt.day, opt.puzzle, day19),
+        20 => advent_of_code::day!(2022, opt.day, opt.puzzle, day20),
         // NEXT PART
         _ => panic!("unknown day {}", opt.day),
     }