Implement 2022 day 20

2022/inputs/19.txt

@@ -0,0 +1,30 @@
+Blueprint 1: Each ore robot costs 3 ore. Each clay robot costs 3 ore. Each obsidian robot costs 3 ore and 16 clay. Each geode robot costs 3 ore and 20 obsidian.
+Blueprint 2: Each ore robot costs 4 ore. Each clay robot costs 3 ore. Each obsidian robot costs 4 ore and 20 clay. Each geode robot costs 2 ore and 15 obsidian.
+Blueprint 3: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 15 clay. Each geode robot costs 3 ore and 8 obsidian.
+Blueprint 4: Each ore robot costs 3 ore. Each clay robot costs 4 ore. Each obsidian robot costs 2 ore and 15 clay. Each geode robot costs 2 ore and 13 obsidian.
+Blueprint 5: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 2 ore and 12 clay. Each geode robot costs 3 ore and 15 obsidian.
+Blueprint 6: Each ore robot costs 2 ore. Each clay robot costs 3 ore. Each obsidian robot costs 3 ore and 11 clay. Each geode robot costs 2 ore and 16 obsidian.
+Blueprint 7: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 8 clay. Each geode robot costs 2 ore and 15 obsidian.
+Blueprint 8: Each ore robot costs 3 ore. Each clay robot costs 4 ore. Each obsidian robot costs 2 ore and 11 clay. Each geode robot costs 2 ore and 10 obsidian.
+Blueprint 9: Each ore robot costs 3 ore. Each clay robot costs 3 ore. Each obsidian robot costs 3 ore and 16 clay. Each geode robot costs 3 ore and 9 obsidian.
+Blueprint 10: Each ore robot costs 4 ore. Each clay robot costs 2 ore. Each obsidian robot costs 2 ore and 16 clay. Each geode robot costs 2 ore and 8 obsidian.
+Blueprint 11: Each ore robot costs 3 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 5 clay. Each geode robot costs 3 ore and 12 obsidian.
+Blueprint 12: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 3 ore and 7 clay. Each geode robot costs 4 ore and 20 obsidian.
+Blueprint 13: Each ore robot costs 3 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 18 clay. Each geode robot costs 2 ore and 11 obsidian.
+Blueprint 14: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 20 clay. Each geode robot costs 2 ore and 8 obsidian.
+Blueprint 15: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 10 clay. Each geode robot costs 2 ore and 7 obsidian.
+Blueprint 16: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 9 clay. Each geode robot costs 2 ore and 20 obsidian.
+Blueprint 17: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 17 clay. Each geode robot costs 2 ore and 13 obsidian.
+Blueprint 18: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 2 ore and 16 clay. Each geode robot costs 4 ore and 16 obsidian.
+Blueprint 19: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 2 ore and 7 clay. Each geode robot costs 4 ore and 13 obsidian.
+Blueprint 20: Each ore robot costs 3 ore. Each clay robot costs 3 ore. Each obsidian robot costs 2 ore and 14 clay. Each geode robot costs 3 ore and 17 obsidian.
+Blueprint 21: Each ore robot costs 3 ore. Each clay robot costs 3 ore. Each obsidian robot costs 3 ore and 19 clay. Each geode robot costs 3 ore and 19 obsidian.
+Blueprint 22: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 7 clay. Each geode robot costs 2 ore and 16 obsidian.
+Blueprint 23: Each ore robot costs 3 ore. Each clay robot costs 3 ore. Each obsidian robot costs 3 ore and 19 clay. Each geode robot costs 3 ore and 17 obsidian.
+Blueprint 24: Each ore robot costs 3 ore. Each clay robot costs 3 ore. Each obsidian robot costs 2 ore and 20 clay. Each geode robot costs 2 ore and 20 obsidian.
+Blueprint 25: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 14 clay. Each geode robot costs 3 ore and 16 obsidian.
+Blueprint 26: Each ore robot costs 4 ore. Each clay robot costs 4 ore. Each obsidian robot costs 3 ore and 5 clay. Each geode robot costs 3 ore and 18 obsidian.
+Blueprint 27: Each ore robot costs 3 ore. Each clay robot costs 4 ore. Each obsidian robot costs 2 ore and 19 clay. Each geode robot costs 2 ore and 12 obsidian.
+Blueprint 28: Each ore robot costs 2 ore. Each clay robot costs 4 ore. Each obsidian robot costs 4 ore and 15 clay. Each geode robot costs 2 ore and 20 obsidian.
+Blueprint 29: Each ore robot costs 3 ore. Each clay robot costs 4 ore. Each obsidian robot costs 3 ore and 6 clay. Each geode robot costs 2 ore and 10 obsidian.
+Blueprint 30: Each ore robot costs 4 ore. Each clay robot costs 3 ore. Each obsidian robot costs 3 ore and 7 clay. Each geode robot costs 3 ore and 9 obsidian.

2022/src/day20.rs

@@ -1,9 +1,135 @@
+use std::cmp::Ordering;
+use std::fmt::Write;
+use std::iter::once;
+
+use anyhow::Context;
 use anyhow::Result;
+use nom::character::complete::newline;
+use nom::multi::many0;
+use nom::sequence::terminated;
+use nom::IResult;
 
-pub fn part1(_input: &[u8]) -> Result<String> {
+use crate::common::parse_input;
-    anyhow::bail!("not implemented")
+
+fn parse_encrypted(input: &[u8]) -> IResult<&[u8], Vec<i64>> {
+    many0(terminated(nom::character::complete::i64, newline))(input)
 }
 
-pub fn part2(_input: &[u8]) -> Result<String> {
+fn step(steps: &[usize], mut start: usize, count: usize) -> usize {
-    anyhow::bail!("not implemented")
+    for _ in 0..(count % (steps.len() - 1)) {
+        start = steps[start];
+    }
+
+    start
+}
+
+#[allow(unused)]
+fn print(encrypted: &[i64], next: &[usize]) {
+    let mut base = String::new();
+
+    let mut start = 0;
+
+    for _ in 0..encrypted.len() {
+        if base != "" {
+            base += ", ";
+        }
+
+        write!(base, "{}", encrypted[start]).unwrap();
+
+        start = next[start];
+    }
+
+    println!("{base}");
+}
+
+fn move_between(prev: &mut [usize], next: &mut [usize], i: usize, before: usize, after: usize) {
+    if before == i || after == i {
+        return;
+    }
+
+    let before_i = prev[i];
+    let after_i = next[i];
+
+    // Remove i from its original place
+    prev[after_i] = before_i;
+    next[before_i] = after_i;
+
+    // Connect i properly to before
+    prev[before] = i;
+    next[i] = before;
+
+    // Connect i properly to after
+    prev[i] = after;
+    next[after] = i;
+}
+
+pub fn part1(input: &[u8]) -> Result<String> {
+    let encrypted = parse_input(input, parse_encrypted)?;
+
+    shuffle(&encrypted, 1)
+}
+
+fn shuffle(encrypted: &[i64], times: usize) -> Result<String> {
+    let mut next: Vec<_> = (1..encrypted.len()).chain(once(0)).collect();
+    let mut prev: Vec<_> = once(encrypted.len() - 1)
+        .chain(0..(encrypted.len() - 1))
+        .collect();
+
+    for _ in 0..times {
+        for (i, &value) in encrypted.iter().enumerate() {
+            match value.cmp(&0) {
+                Ordering::Less => {
+                    let before = step(&prev, i, (-value) as usize);
+                    let after = prev[before];
+
+                    move_between(&mut prev, &mut next, i, before, after);
+                }
+                Ordering::Equal => continue,
+                Ordering::Greater => {
+                    let after = step(&next, i, value as usize);
+                    let before = next[after];
+
+                    move_between(&mut prev, &mut next, i, before, after);
+                }
+            }
+
+            // print(&encrypted, &next);
+        }
+    }
+
+    let mut start = encrypted
+        .iter()
+        .position(|&v| v == 0)
+        .context("Could not find zero")?;
+
+    let mut sum = 0;
+
+    for _ in 0..3 {
+        start = step(&next, start, 1000);
+        sum += encrypted[start];
+    }
+
+    Ok(sum.to_string())
+}
+
+pub fn part2(input: &[u8]) -> Result<String> {
+    const ENCRYPTION_KEY: i64 = 811589153;
+
+    let mut encrypted = parse_input(input, parse_encrypted)?;
+
+    encrypted.iter_mut().for_each(|v| *v *= ENCRYPTION_KEY);
+
+    shuffle(&encrypted, 10)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const SAMPLE: &[u8] = include_bytes!("samples/20.txt");
+
+    #[test]
+    fn sample_part1() {
+        assert_eq!(part1(SAMPLE).unwrap(), "3");
+    }
 }

2022/src/samples/19.txt

@@ -0,0 +1,11 @@
+Blueprint 1:
+  Each ore robot costs 4 ore.
+  Each clay robot costs 2 ore.
+  Each obsidian robot costs 3 ore and 14 clay.
+  Each geode robot costs 2 ore and 7 obsidian.
+
+Blueprint 2:
+  Each ore robot costs 2 ore.
+  Each clay robot costs 3 ore.
+  Each obsidian robot costs 3 ore and 8 clay.
+  Each geode robot costs 3 ore and 12 obsidian.

2022/src/samples/20.txt

@@ -0,0 +1,7 @@
+1
+2
+-3
+3
+-2
+0
+4