wip: cloned graph

Squashed commit of the following:

commit 000001603e10102f634c2f4ca7eb310ec72f1863
Author: Matej Janežič <janezic.mj@gmail.com>
Date:   Wed Dec 6 20:47:26 2023 +0100

    day(5): ranges

commit 0000015049
Author: Matej Janežič <janezic.mj@gmail.com>
Date:   Wed Dec 6 18:58:58 2023 +0100

    wip: solve with range type

README.md

@@ -1,4 +1,3 @@
-![ci](https://github.com/janezicmatej/aoc2023/actions/workflows/ci.yml/badge.svg)
 # Advent-of-Code 2023
 *This is a dumbed down version of [fspoettel/advent-of-code-rust](https://github.com/fspoettel/advent-of-code-rust) with some extra features*
 

data/examples/02.txt

@@ -0,0 +1,6 @@
+Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green
+

data/examples/03.txt

@@ -0,0 +1,10 @@
+467..114..
+...*......
+..35..633.
+......#...
+617*......
+.....+.58.
+..592.....
+......755.
+...$.*....
+.664.598..

data/examples/04.txt

@@ -0,0 +1,6 @@
+Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53
+Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19
+Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1
+Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83
+Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36
+Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11

data/examples/05.txt

@@ -0,0 +1,33 @@
+seeds: 79 14 55 13
+
+seed-to-soil map:
+50 98 2
+52 50 48
+
+soil-to-fertilizer map:
+0 15 37
+37 52 2
+39 0 15
+
+fertilizer-to-water map:
+49 53 8
+0 11 42
+42 0 7
+57 7 4
+
+water-to-light map:
+88 18 7
+18 25 70
+
+light-to-temperature map:
+45 77 23
+81 45 19
+68 64 13
+
+temperature-to-humidity map:
+0 69 1
+1 0 69
+
+humidity-to-location map:
+60 56 37
+56 93 4

data/examples/06.txt

@@ -0,0 +1,2 @@
+Time:      7  15   30
+Distance:  9  40  200

data/examples/07.txt

@@ -0,0 +1,5 @@
+32T3K 765
+T55J5 684
+KK677 28
+KTJJT 220
+QQQJA 483

data/examples/08-1.txt

@@ -0,0 +1,5 @@
+LLR
+
+AAA = (BBB, BBB)
+BBB = (AAA, ZZZ)
+ZZZ = (ZZZ, ZZZ)

data/examples/08-2.txt

@@ -0,0 +1,10 @@
+LR
+
+11A = (11B, XXX)
+11B = (XXX, 11Z)
+11Z = (11B, XXX)
+22A = (22B, XXX)
+22B = (22C, 22C)
+22C = (22Z, 22Z)
+22Z = (22B, 22B)
+XXX = (XXX, XXX)

data/examples/09.txt

@@ -0,0 +1,3 @@
+0 3 6 9 12 15
+1 3 6 10 15 21
+10 13 16 21 30 45

data/examples/10-1.txt

@@ -0,0 +1,5 @@
+..F7.
+.FJ|.
+SJ.L7
+|F--J
+LJ...

data/examples/10-2.txt

@@ -0,0 +1,10 @@
+FF7FSF7F7F7F7F7F---7
+L|LJ||||||||||||F--J
+FL-7LJLJ||||||LJL-77
+F--JF--7||LJLJ7F7FJ-
+L---JF-JLJ.||-FJLJJ7
+|F|F-JF---7F7-L7L|7|
+|FFJF7L7F-JF7|JL---7
+7-L-JL7||F7|L7F-7F7|
+L.L7LFJ|||||FJL7||LJ
+L7JLJL-JLJLJL--JLJ.L

data/examples/11.txt

@@ -0,0 +1,10 @@
+...#......
+.......#..
+#.........
+..........
+......#...
+.#........
+.........#
+..........
+.......#..
+#...#.....

data/examples/12.txt

@@ -0,0 +1,6 @@
+???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1

data/examples/13.txt

@@ -0,0 +1,15 @@
+#.##..##.
+..#.##.#.
+##......#
+##......#
+..#.##.#.
+..##..##.
+#.#.##.#.
+
+#...##..#
+#....#..#
+..##..###
+#####.##.
+#####.##.
+..##..###
+#....#..#

data/examples/14.txt

@@ -0,0 +1,10 @@
+O....#....
+O.OO#....#
+.....##...
+OO.#O....O
+.O.....O#.
+O.#..O.#.#
+..O..#O..O
+.......O..
+#....###..
+#OO..#....

data/examples/15.txt

@@ -0,0 +1 @@
+rn=1,cm-,qp=3,cm=2,qp-,pc=4,ot=9,ab=5,pc-,pc=6,ot=7

data/examples/16.txt

@@ -0,0 +1,10 @@
+.|...\....
+|.-.\.....
+.....|-...
+........|.
+..........
+.........\
+..../.\\..
+.-.-/..|..
+.|....-|.\
+..//.|....

data/examples/17.txt

@@ -0,0 +1,13 @@
+2413432311323
+3215453535623
+3255245654254
+3446585845452
+4546657867536
+1438598798454
+4457876987766
+3637877979653
+4654967986887
+4564679986453
+1224686865563
+2546548887735
+4322674655533

data/examples/18.txt

@@ -0,0 +1,14 @@
+R 6 (#70c710)
+D 5 (#0dc571)
+L 2 (#5713f0)
+D 2 (#d2c081)
+R 2 (#59c680)
+D 2 (#411b91)
+L 5 (#8ceee2)
+U 2 (#caa173)
+L 1 (#1b58a2)
+U 2 (#caa171)
+R 2 (#7807d2)
+U 3 (#a77fa3)
+L 2 (#015232)
+U 2 (#7a21e3)

data/examples/19.txt

@@ -0,0 +1,17 @@
+px{a<2006:qkq,m>2090:A,rfg}
+pv{a>1716:R,A}
+lnx{m>1548:A,A}
+rfg{s<537:gd,x>2440:R,A}
+qs{s>3448:A,lnx}
+qkq{x<1416:A,crn}
+crn{x>2662:A,R}
+in{s<1351:px,qqz}
+qqz{s>2770:qs,m<1801:hdj,R}
+gd{a>3333:R,R}
+hdj{m>838:A,pv}
+
+{x=787,m=2655,a=1222,s=2876}
+{x=1679,m=44,a=2067,s=496}
+{x=2036,m=264,a=79,s=2244}
+{x=2461,m=1339,a=466,s=291}
+{x=2127,m=1623,a=2188,s=1013}

data/examples/20.txt

@@ -0,0 +1,5 @@
+broadcaster -> a, b, c
+%a -> b
+%b -> c
+%c -> inv
+&inv -> a

src/bin/01.rs

@@ -1,66 +1,46 @@
 pub fn part_one(input: &str) -> Option<u32> {
     let mut c = 0;
+
     for line in input.lines() {
-        let mut itr = line.chars().filter(|x| x.is_ascii_digit());
+        let mut itr = line.chars().filter(char::is_ascii_digit);
 
-        let f = itr.next().unwrap();
-        let l = itr.last().unwrap_or(f);
+        let first = itr.next().unwrap();
+        let last = itr.last().unwrap_or(first);
 
-        c += format!("{f}{l}").parse::<u32>().unwrap();
+        c += format!("{first}{last}").parse::<u32>().unwrap();
     }
 
     Some(c)
 }
 
-pub fn part_two(input: &str) -> Option<u32> {
-    let mut c = 0;
-    let nums = [
+const NUMS: [&str; 9] = [
     "one", "two", "three", "four", "five", "six", "seven", "eight", "nine",
-    ];
+];
+
+pub fn part_two(input: &str) -> Option<u32> {
+    // NOTE:(matej) this solution is O(n^2) since we search string for each substring separately
+
+    let mut c = 0;
+    let nums: Vec<(u32, String)> = (1..=9).zip(NUMS.into_iter().map(String::from)).collect();
 
     for line in input.lines() {
-        let mut first = (line.len(), None);
-        let mut last = (0, None);
+        let mut all_matches = Vec::new();
 
-        for (idx, n) in nums.iter().enumerate() {
-            let matches: Vec<_> = line.match_indices(n).collect();
-
-            if matches.is_empty() {
-                continue;
+        for (n, str_n) in nums.iter() {
+            all_matches.extend(line.match_indices(str_n).map(|(x, _)| (x, *n)));
         }
 
-            let m = matches.first().unwrap();
+        all_matches.extend(
+            line.chars()
+                .enumerate()
+                .filter(|(_, c)| c.is_ascii_digit())
+                .map(|(idx, c)| (idx, c.to_digit(10).unwrap())),
+        );
 
-            if m.0 < first.0 {
-                first = (m.0, Some(idx + 1));
-            }
+        let first = all_matches.iter().min_by_key(|&(idx, _)| idx).unwrap().1;
+        let last = all_matches.iter().max_by_key(|&(idx, _)| idx).unwrap().1;
 
-            let m = matches.last().unwrap();
-
-            if m.0 >= last.0 {
-                last = (m.0, Some(idx + 1));
-            }
-        }
-        let mut itr = line.chars().enumerate().filter(|(_, x)| x.is_ascii_digit());
-
-        let Some(f) = itr.next() else {
-            c += format!("{}{}", first.1.unwrap(), last.1.unwrap())
-                .parse::<u32>()
-                .unwrap();
-            continue;
-        };
-        let l = itr.last().unwrap_or(f);
-
-        if f.0 < first.0 {
-            first = (f.0, f.1.to_string().parse().ok());
-        }
-
-        if l.0 >= last.0 {
-            last = (l.0, l.1.to_string().parse().ok());
-        }
-        c += format!("{}{}", first.1.unwrap(), last.1.unwrap())
-            .parse::<u32>()
-            .unwrap();
+        c += first * 10 + last;
     }
 
     Some(c)

src/bin/02.rs

@@ -0,0 +1,84 @@
+use std::str::FromStr;
+
+use aoc::parsers::to_vec;
+
+struct Game {
+    id: u32,
+    balls: Vec<(u32, String)>,
+}
+
+impl FromStr for Game {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let rest = s.strip_prefix("Game ").unwrap();
+        let (id, rest) = rest.split_once(':').unwrap();
+        let id = id.parse().unwrap();
+
+        let balls = rest
+            .split([',', ';'])
+            .map(|x| x.strip_prefix(' ').unwrap().split_once(' ').unwrap())
+            .map(|(n, c)| (n.parse::<u32>().unwrap(), c.to_string()))
+            .collect();
+
+        Ok(Game { id, balls })
+    }
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let games: Vec<Game> = to_vec(input, '\n');
+    let rules = [(12, "red"), (13, "green"), (14, "blue")];
+
+    Some(
+        games
+            .iter()
+            .filter(|g| {
+                !g.balls
+                    .iter()
+                    .any(|(n, c)| rules.iter().any(|(rn, rc)| c == rc && n > rn))
+            })
+            .map(|g| g.id)
+            .sum(),
+    )
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let games: Vec<Game> = to_vec(input, '\n');
+
+    let mut total_power = 0;
+
+    for g in games {
+        let power: u32 = ["blue", "red", "green"]
+            .iter()
+            .map(|&c| {
+                g.balls
+                    .iter()
+                    .filter(|(_, cd)| c == cd.as_str())
+                    .map(|(n, _)| n)
+                    .max()
+                    .unwrap()
+            })
+            .product();
+
+        total_power += power;
+    }
+
+    Some(total_power)
+}
+
+aoc::solution!(2);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(part_one(&aoc::template::read_file("examples", 2)), Some(8));
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 2)),
+            Some(2286)
+        );
+    }
+}

src/bin/03.rs

@@ -0,0 +1,104 @@
+struct MappedPart {
+    number: u32,
+    line: usize,
+    start: usize,
+    end: usize,
+}
+
+impl MappedPart {
+    fn is_adjacent(&self, line: usize, column: usize) -> bool {
+        self.line.abs_diff(line) <= 1
+            && (self.start.abs_diff(column) <= 1 || self.end.abs_diff(column) <= 1)
+    }
+}
+
+fn build_map(input: &str) -> Vec<MappedPart> {
+    let mut numbers = Vec::new();
+    for (idl, line) in input.lines().enumerate() {
+        let mut index = 0;
+        for n in line.split(|c: char| !c.is_ascii_digit()) {
+            if n.is_empty() {
+                index += 1;
+                continue;
+            }
+
+            let num: u32 = n.parse().unwrap();
+            let num_len = n.len();
+
+            numbers.push(MappedPart {
+                number: num,
+                line: idl,
+                start: index,
+                end: index + num_len - 1,
+            });
+
+            index += num_len + 1;
+        }
+    }
+
+    numbers
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let numbers = build_map(input);
+
+    let mut part_numbers = 0;
+
+    for (idl, line) in input.lines().enumerate() {
+        for (idc, _) in line
+            .chars()
+            .enumerate()
+            .filter(|(_, c)| !(*c == '.' || c.is_ascii_digit()))
+        {
+            part_numbers += numbers
+                .iter()
+                .filter(|mp| mp.is_adjacent(idl, idc))
+                .map(|mp| mp.number)
+                .sum::<u32>();
+        }
+    }
+
+    Some(part_numbers)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let numbers = build_map(input);
+
+    let mut gear_ratios = 0;
+
+    for (idl, line) in input.lines().enumerate() {
+        for (idc, _) in line.chars().enumerate().filter(|(_, c)| *c == '*') {
+            let touching: Vec<_> = numbers
+                .iter()
+                .filter(|mp| mp.is_adjacent(idl, idc))
+                .map(|mp| mp.number)
+                .collect();
+            if touching.len() == 2 {
+                gear_ratios += touching.iter().product::<u32>();
+            }
+        }
+    }
+
+    Some(gear_ratios)
+}
+
+aoc::solution!(3);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 3)),
+            Some(4361)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 3)),
+            Some(467835)
+        );
+    }
+}

src/bin/04.rs

@@ -0,0 +1,79 @@
+use std::str::FromStr;
+
+use aoc::parsers::to_vec;
+
+struct ParseCardError;
+
+struct Card {
+    winning: Vec<u32>,
+    numbers: Vec<u32>,
+}
+
+impl FromStr for Card {
+    type Err = ParseCardError;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (_, rest) = s.split_once(": ").unwrap();
+        let (win, my) = rest.split_once(" | ").unwrap();
+
+        let winning: Vec<u32> = to_vec(win, ' ');
+        let numbers: Vec<u32> = to_vec(my, ' ');
+
+        Ok(Card { winning, numbers })
+    }
+}
+
+impl Card {
+    fn n_matches(&self) -> usize {
+        self.numbers
+            .iter()
+            .filter(|n| self.winning.contains(n))
+            .count()
+    }
+    fn score(&self) -> u32 {
+        let c = self.n_matches();
+
+        if c == 0 {
+            return 0;
+        }
+
+        2_u32.pow((self.n_matches() - 1) as u32)
+    }
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    Some(
+        input
+            .lines()
+            .filter_map(|l| l.parse::<Card>().ok())
+            .map(|g| g.score())
+            .sum(),
+    )
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let cards: Vec<Card> = to_vec(input, '\n');
+    let mut multiples = vec![1; cards.len()];
+
+    for (i, card) in cards.iter().enumerate() {
+        for j in 0..card.n_matches() {
+            multiples[i + j + 1] += multiples[i];
+        }
+    }
+
+    Some(multiples.iter().sum::<u32>())
+}
+
+aoc::solution!(4);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(part_one(&aoc::template::read_file("examples", 4)), Some(13));
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(part_two(&aoc::template::read_file("examples", 4)), Some(30));
+    }
+}

src/bin/05.rs

@@ -0,0 +1,170 @@
+use std::{
+    cmp::{max, min},
+    fmt::Debug,
+    ops::RangeInclusive,
+    str::FromStr,
+};
+
+use aoc::parsers::to_vec;
+
+trait RangeInclusiveExt {
+    fn overlaps(&self, other: &Self) -> bool;
+}
+
+impl<T> RangeInclusiveExt for RangeInclusive<T>
+where
+    T: PartialOrd,
+{
+    fn overlaps(&self, other: &Self) -> bool {
+        self.contains(other.start()) || self.contains(other.end())
+    }
+}
+
+fn build_range(start: u64, range: u64) -> RangeInclusive<u64> {
+    start..=(start + range - 1)
+}
+
+#[derive(Debug)]
+struct Mapping {
+    pub source: RangeInclusive<u64>,
+    pub destination: RangeInclusive<u64>,
+}
+
+struct ParseMappingError;
+
+impl FromStr for Mapping {
+    type Err = ParseMappingError;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let nums: Vec<u64> = to_vec(s, ' ');
+
+        Ok(Self {
+            destination: build_range(nums[0], nums[2]),
+            source: build_range(nums[1], nums[2]),
+        })
+    }
+}
+
+impl Mapping {
+    fn map(&self, n: u64) -> u64 {
+        let shift = n - self.source.start();
+        self.destination.start() + shift
+    }
+
+    fn map_range(&self, r: RangeInclusive<u64>) -> RangeInclusive<u64> {
+        self.map(*r.start())..=(self.map(*r.end()))
+    }
+
+    fn split_range(&self, r: RangeInclusive<u64>) -> [Option<RangeInclusive<u64>>; 3] {
+        let mut fences = [
+            *r.start(),
+            *r.end() + 1,
+            max(*self.source.start(), *r.start()),
+            min(*self.source.end() + 1, *r.end() + 1),
+        ];
+
+        fences.sort();
+
+        const ARRAY_REPEAT_VALUE: Option<RangeInclusive<u64>> = None;
+        let mut v = [ARRAY_REPEAT_VALUE; 3];
+
+        for i in 0..3 {
+            let f = fences[i];
+            let nf = fences[i + 1];
+            if f != nf {
+                v[i] = Some(f..=(nf - 1))
+            }
+        }
+        v
+    }
+}
+
+fn parse_map(maps: &str) -> Vec<Vec<Mapping>> {
+    let mut res = Vec::new();
+
+    for mapper in maps.split("\n\n") {
+        res.push(
+            mapper
+                .lines()
+                .skip(1)
+                .filter_map(|m| m.parse().ok())
+                .collect(),
+        )
+    }
+
+    res
+}
+
+pub fn part_one(input: &str) -> Option<u64> {
+    let (first, rest) = input.split_once("\n\n").unwrap();
+    let maps = parse_map(rest);
+    let seeds = to_vec::<u64, _>(first.strip_prefix("seeds: ").unwrap(), ' ');
+
+    let mut m = u64::MAX;
+
+    for seed in seeds.iter() {
+        let mut s = *seed;
+        'maps: for map in maps.iter() {
+            for inner in map.iter() {
+                if inner.source.contains(&s) {
+                    s = inner.map(s);
+                    continue 'maps;
+                }
+            }
+        }
+
+        m = min(m, s)
+    }
+
+    Some(m)
+}
+
+pub fn part_two(input: &str) -> Option<u64> {
+    let (first, rest) = input.split_once("\n\n").unwrap();
+    let maps = parse_map(rest);
+    let mut seeds_ranges: Vec<_> = to_vec::<u64, _>(first.strip_prefix("seeds: ").unwrap(), ' ')
+        .chunks(2)
+        .map(|x| build_range(x[0], x[1]))
+        .collect();
+
+    for mapping in maps.iter() {
+        let mut new_ranges = Vec::new();
+
+        'queue: while let Some(rng) = seeds_ranges.pop() {
+            for map in mapping {
+                if map.source.overlaps(&rng) {
+                    let [pre, to_map, post] = map.split_range(rng);
+                    new_ranges.push(map.map_range(to_map.unwrap()));
+                    for r in [pre, post].into_iter().flatten() {
+                        seeds_ranges.push(r);
+                    }
+                    continue 'queue;
+                }
+            }
+
+            new_ranges.push(rng);
+        }
+
+        seeds_ranges = new_ranges;
+    }
+
+    seeds_ranges
+        .iter()
+        .map(RangeInclusive::start)
+        .min()
+        .copied()
+}
+
+aoc::solution!(5);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(part_one(&aoc::template::read_file("examples", 5)), Some(35));
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(part_two(&aoc::template::read_file("examples", 5)), Some(46));
+    }
+}

src/bin/06.rs

@@ -0,0 +1,67 @@
+fn win_options((time, distance): (u64, u64)) -> u64 {
+    let discriminant = ((time.pow(2) - 4 * distance) as f64).sqrt();
+
+    let first_zero = (time as f64 - discriminant) / 2.0;
+    let mut second_zero = (time as f64 + discriminant) / 2.0;
+
+    if second_zero.fract() == 0.0 {
+        second_zero -= 1.0
+    }
+
+    second_zero as u64 - first_zero as u64
+}
+
+pub fn part_one(input: &str) -> Option<u64> {
+    let [time, distance] = input
+        .lines()
+        .map(|l| {
+            l.split_whitespace()
+                .skip(1)
+                .filter_map(|n| n.parse().ok())
+                .collect::<Vec<u64>>()
+        })
+        .collect::<Vec<_>>()
+        .try_into()
+        .ok()?;
+
+    Some(time.into_iter().zip(distance).map(win_options).product())
+}
+
+pub fn part_two(input: &str) -> Option<u64> {
+    let [time, distance] = input
+        .lines()
+        .filter_map(|l| {
+            l.split_whitespace()
+                .skip(1)
+                .flat_map(|x| x.chars())
+                .collect::<String>()
+                .parse()
+                .ok()
+        })
+        .collect::<Vec<_>>()
+        .try_into()
+        .ok()?;
+
+    Some(win_options((time, distance)))
+}
+
+aoc::solution!(6);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 6)),
+            Some(288)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 6)),
+            Some(71503)
+        );
+    }
+}

src/bin/07.rs

@@ -0,0 +1,191 @@
+use std::{cmp::Ordering, collections::HashMap, str::FromStr};
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Hash)]
+enum Label {
+    Ace = 14,
+    King = 13,
+    Queen = 12,
+    Jack = 11,
+    Ten = 10,
+    Nine = 9,
+    Eight = 8,
+    Seven = 7,
+    Six = 6,
+    Five = 5,
+    Four = 4,
+    Three = 3,
+    Two = 2,
+    Joker = 1,
+}
+
+impl From<char> for Label {
+    fn from(value: char) -> Self {
+        use Label::*;
+        match value {
+            'A' => Ace,
+            'K' => King,
+            'Q' => Queen,
+            'J' => Jack,
+            'T' => Ten,
+            '9' => Nine,
+            '8' => Eight,
+            '7' => Seven,
+            '6' => Six,
+            '5' => Five,
+            '4' => Four,
+            '3' => Three,
+            '2' => Two,
+            'X' => Joker,
+            _ => unreachable!(),
+        }
+    }
+}
+
+#[derive(Debug)]
+struct ParseHandError;
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+struct Hand {
+    labels: [Label; 5],
+}
+
+impl FromStr for Hand {
+    type Err = ParseHandError;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let labels = s
+            .chars()
+            .map(Label::from)
+            .collect::<Vec<_>>()
+            .try_into()
+            .map_err(|_| ParseHandError)?;
+        Ok(Hand { labels })
+    }
+}
+
+impl PartialOrd for Hand {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Hand {
+    fn cmp(&self, other: &Self) -> Ordering {
+        let sf = HandType::from(*self);
+        let so = HandType::from(*other);
+
+        sf.cmp(&so).then({
+            let mut c = Ordering::Equal;
+            for i in 0..5 {
+                c = self.labels[i].cmp(&other.labels[i]);
+                if c != Ordering::Equal {
+                    break;
+                }
+            }
+            c
+        })
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+enum HandType {
+    Five = 6,
+    Four = 5,
+    FullHouse = 4,
+    Three = 3,
+    TwoPair = 2,
+    Pair = 1,
+    HighCard = 0,
+}
+
+impl From<Hand> for HandType {
+    fn from(value: Hand) -> Self {
+        let mut map = HashMap::new();
+
+        for c in value.labels {
+            *map.entry(c).or_insert(0) += 1;
+        }
+
+        let joker = map.remove(&Label::Joker).unwrap_or(0);
+
+        let is_n_k = |n| joker == n || map.values().filter(|&x| *x == n - joker).count() > 0;
+
+        if is_n_k(5) {
+            return Self::Five;
+        }
+        if is_n_k(4) {
+            return Self::Four;
+        }
+        // full house
+        if map.values().count() <= 2 {
+            return Self::FullHouse;
+        }
+        if is_n_k(3) {
+            return Self::Three;
+        }
+        // two pair
+        if map.values().count() <= 3 {
+            return Self::TwoPair;
+        }
+        if is_n_k(2) {
+            return Self::Pair;
+        }
+
+        Self::HighCard
+    }
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let mut v = input
+        .lines()
+        .filter_map(|l| l.split_once(' '))
+        .map(|(f, s)| (f.parse::<Hand>().unwrap(), s.parse::<u32>().unwrap()))
+        .collect::<Vec<_>>();
+
+    v.sort_by(|f, o| f.0.cmp(&o.0));
+
+    Some(
+        v.into_iter()
+            .enumerate()
+            .map(|(i, x)| (i as u32 + 1) * x.1)
+            .sum::<u32>(),
+    )
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let mut v = input
+        .replace('J', "X")
+        .lines()
+        .filter_map(|l| l.split_once(' '))
+        .map(|(f, s)| (f.parse::<Hand>().unwrap(), s.parse::<u32>().unwrap()))
+        .collect::<Vec<_>>();
+
+    v.sort_by(|f, o| f.0.cmp(&o.0));
+
+    Some(
+        v.into_iter()
+            .enumerate()
+            .map(|(i, x)| (i as u32 + 1) * x.1)
+            .sum::<u32>(),
+    )
+}
+
+aoc::solution!(7);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 7)),
+            Some(6440)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 7)),
+            Some(5905)
+        );
+    }
+}

src/bin/08.rs

@@ -0,0 +1,95 @@
+use std::collections::HashMap;
+
+use aoc::lcm;
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let mut map = HashMap::new();
+
+    let (directions, map_data) = input.split_once("\n\n")?;
+    for line in map_data.lines() {
+        let (k, v) = line.split_once(" = ")?;
+        let v = v.strip_prefix('(')?;
+        let v = v.strip_suffix(')')?;
+        let (l, r) = v.split_once(", ")?;
+
+        *map.entry(k).or_default() = (l, r);
+    }
+
+    let mut counter = 0;
+    let mut loc = "AAA";
+
+    for d in directions.chars().cycle() {
+        if loc == "ZZZ" {
+            break;
+        }
+
+        counter += 1;
+        let (l, r) = map[loc];
+
+        match d {
+            'L' => loc = l,
+            'R' => loc = r,
+            _ => unimplemented!(),
+        }
+    }
+
+    Some(counter)
+}
+
+pub fn part_two(input: &str) -> Option<u64> {
+    let mut map = HashMap::new();
+
+    let (directions, map_data) = input.split_once("\n\n")?;
+    for line in map_data.lines() {
+        let (k, v) = line.split_once(" = ")?;
+        let v = v.strip_prefix('(')?;
+        let v = v.strip_suffix(')')?;
+        let (l, r) = v.split_once(", ")?;
+
+        *map.entry(k).or_default() = (l, r);
+    }
+
+    let mut res = 1;
+
+    for k in map.keys().filter(|x| x.ends_with('A')) {
+        let mut location = *k;
+
+        for (i, d) in directions.chars().cycle().enumerate() {
+            let (l, r) = map[location];
+
+            location = match d {
+                'L' => l,
+                'R' => r,
+                _ => unimplemented!(),
+            };
+
+            if location.ends_with('Z') {
+                res = lcm(res, i + 1);
+                break;
+            }
+        }
+    }
+
+    Some(res as u64)
+}
+
+aoc::solution!(8);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file_part("examples", 8, 1)),
+            Some(6)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file_part("examples", 8, 2)),
+            Some(6)
+        );
+    }
+}

src/bin/09.rs

@@ -0,0 +1,90 @@
+use std::collections::VecDeque;
+
+fn find_history(v: VecDeque<i32>) -> VecDeque<VecDeque<i32>> {
+    let mut s = VecDeque::new();
+    s.push_back(v);
+
+    loop {
+        let mut all_zeros = true;
+
+        let last = s.back().unwrap();
+        let mut new = VecDeque::new();
+        for i in 0..(last.len() - 1) {
+            let diff = last[i + 1] - last[i];
+            if diff != 0 {
+                all_zeros = false;
+            }
+
+            new.push_back(diff);
+        }
+        s.push_back(new);
+
+        if all_zeros {
+            break;
+        }
+    }
+
+    s
+}
+
+fn extrapolate_forward(v: VecDeque<i32>) -> i32 {
+    let mut s = find_history(v);
+
+    for i in (1..s.len()).rev() {
+        let adder = *s[i].back().unwrap();
+        let last = *s[i - 1].back().unwrap();
+        s[i - 1].push_back(last + adder);
+    }
+
+    *s[0].back().unwrap()
+}
+
+fn extrapolate_back(v: VecDeque<i32>) -> i32 {
+    let mut s = find_history(v);
+
+    for i in (1..s.len()).rev() {
+        let adder = *s[i].front().unwrap();
+        let first = *s[i - 1].front().unwrap();
+        s[i - 1].push_front(first - adder);
+    }
+
+    *s[0].front().unwrap()
+}
+
+pub fn part_one(input: &str) -> Option<i32> {
+    Some(
+        input
+            .lines()
+            .map(|x| x.split(' ').filter_map(|y| y.parse().ok()).collect())
+            .map(extrapolate_forward)
+            .sum(),
+    )
+}
+
+pub fn part_two(input: &str) -> Option<i32> {
+    Some(
+        input
+            .lines()
+            .map(|x| x.split(' ').filter_map(|y| y.parse().ok()).collect())
+            .map(extrapolate_back)
+            .sum(),
+    )
+}
+
+aoc::solution!(9);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 9)),
+            Some(114)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(part_two(&aoc::template::read_file("examples", 9)), Some(2));
+    }
+}

src/bin/10.rs

@@ -0,0 +1,158 @@
+use std::collections::HashSet;
+
+const DIRS: [(isize, isize); 4] = [(1, 0), (0, 1), (-1, 0), (0, -1)];
+
+fn next_move(dy: isize, dx: isize, c: char) -> Option<(isize, isize)> {
+    Some(match (dy, dx) {
+        (1, 0) => match c {
+            '|' => (1, 0),
+            'J' => (0, -1),
+            'L' => (0, 1),
+            _ => None?,
+        },
+        (0, 1) => match c {
+            '-' => (0, 1),
+            '7' => (1, 0),
+            'J' => (-1, 0),
+            _ => None?,
+        },
+        (-1, 0) => match c {
+            '|' => (-1, 0),
+            '7' => (0, -1),
+            'F' => (0, 1),
+            _ => None?,
+        },
+        (0, -1) => match c {
+            '-' => (0, -1),
+            'F' => (1, 0),
+            'L' => (-1, 0),
+            _ => None?,
+        },
+        _ => unreachable!(),
+    })
+}
+
+fn parse_input(input: &str) -> (Vec<Vec<char>>, (isize, isize)) {
+    let pipes: Vec<Vec<char>> = input.lines().map(|x| x.chars().collect()).collect();
+
+    let start = pipes
+        .iter()
+        .enumerate()
+        .find_map(|(i, x)| {
+            x.iter()
+                .enumerate()
+                .map(|(j, y)| (i, j, y))
+                .find(|(_, _, &x)| x == 'S')
+        })
+        .map(|(j, i, _)| (j as isize, i as isize))
+        .unwrap();
+
+    (pipes, start)
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let (pipes, start) = parse_input(input);
+
+    'start_dir: for d in DIRS {
+        let (mut dy, mut dx) = d;
+        let (mut ly, mut lx) = (start.0 + d.0, start.1 + d.1);
+        let mut counter = 0;
+
+        while start != (ly, lx) {
+            let p = match pipes.get(ly as usize).and_then(|x| x.get(lx as usize)) {
+                Some(x) => *x,
+                None => continue 'start_dir,
+            };
+
+            match next_move(dy, dx, p) {
+                Some((ndy, ndx)) => (dy, dx) = (ndy, ndx),
+                None => continue 'start_dir,
+            }
+
+            counter += 1;
+            (ly, lx) = (ly + dy, lx + dx);
+        }
+
+        return Some((counter + 1) / 2);
+    }
+
+    None
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let (pipes, start) = parse_input(input);
+
+    let mut border = HashSet::with_capacity(pipes.len() * pipes[0].len());
+
+    'start_dir: for d in DIRS {
+        border.clear();
+        border.insert(start);
+
+        let (mut dy, mut dx) = d;
+        let (mut ly, mut lx) = (start.0 + d.0, start.1 + d.1);
+
+        while start != (ly, lx) {
+            let p = match pipes.get(ly as usize).and_then(|x| x.get(lx as usize)) {
+                Some(x) => *x,
+                None => continue 'start_dir,
+            };
+
+            match next_move(dy, dx, p) {
+                Some((ndx, ndy)) => {
+                    (dy, dx) = (ndx, ndy);
+                    border.insert((ly, lx));
+                }
+                None => continue 'start_dir,
+            }
+
+            (ly, lx) = (ly + dy, lx + dx);
+        }
+
+        break;
+    }
+
+    let mut counter = 0;
+
+    for (sy, sx) in (1..pipes.len())
+        .map(|x| (x, 0))
+        .chain((0..pipes[0].len()).map(|x| (0, x)))
+    {
+        let mut inside = false;
+        for range in 0.. {
+            if let Some(c) = pipes.get(sy + range).and_then(|x| x.get(sx + range)) {
+                let is_border = border.contains(&((sy + range) as isize, (sx + range) as isize));
+                if is_border && !['7', 'L'].contains(c) {
+                    inside = !inside;
+                }
+                if !is_border && inside {
+                    counter += 1;
+                }
+            } else {
+                break;
+            }
+        }
+    }
+
+    Some(counter)
+}
+
+aoc::solution!(10);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file_part("examples", 10, 1)),
+            Some(8)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file_part("examples", 10, 2)),
+            Some(10)
+        );
+    }
+}

src/bin/11.rs

@@ -0,0 +1,74 @@
+use std::collections::HashSet;
+
+fn parse_input(input: &str) -> (Vec<(usize, usize)>, HashSet<usize>, HashSet<usize>) {
+    let mut galaxies = Vec::new();
+    let mut rows = HashSet::from_iter(0..input.lines().count());
+    let mut columns = HashSet::from_iter(0..input.lines().next().unwrap().len());
+
+    for (y, line) in input.lines().enumerate() {
+        for (x, c) in line.chars().enumerate() {
+            if c == '#' {
+                galaxies.push((y, x));
+                rows.remove(&y);
+                columns.remove(&x);
+            }
+        }
+    }
+
+    (galaxies, rows, columns)
+}
+
+fn solve(input: &str, explode: usize) -> Option<usize> {
+    let (galaxies, rows, columns) = parse_input(input);
+
+    let mut counter = 0;
+
+    for ((y1, x1), (y2, x2)) in galaxies
+        .iter()
+        .copied()
+        .enumerate()
+        .flat_map(|(i, x)| galaxies.iter().skip(i + 1).copied().map(move |y| (x, y)))
+    {
+        let y_abs = y1.abs_diff(y2);
+        let x_abs = x1.abs_diff(x2);
+        let x_extra = columns
+            .iter()
+            .filter(|x| (x1..=x2).contains(x) || (x2..=x1).contains(x))
+            .count();
+        let y_extra = rows
+            .iter()
+            .filter(|y| (y1..=y2).contains(y) || (y2..=y1).contains(y))
+            .count();
+        counter += x_abs + y_abs + (x_extra + y_extra) * (explode - 1);
+    }
+
+    Some(counter)
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    solve(input, 2)
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    solve(input, 1_000_000)
+}
+
+aoc::solution!(11);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 11)),
+            Some(374)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        let input = aoc::template::read_file("examples", 11);
+        assert_eq!(solve(&input, 10), Some(1030));
+        assert_eq!(solve(&input, 100), Some(8410));
+    }
+}

src/bin/12.rs

@@ -0,0 +1,114 @@
+use std::{collections::HashMap, iter::once};
+
+fn is_valid(sequence: &[char], ptr: usize, group: usize) -> bool {
+    let edges_front = *once(&'.').chain(sequence.iter()).nth(ptr).unwrap() != '#';
+    let edges_back = *sequence.iter().chain(once(&'.')).nth(ptr + group).unwrap() != '#';
+
+    let filled = sequence
+        .iter()
+        .chain(once(&'.').cycle())
+        .skip(ptr)
+        .take(group)
+        .all(|x| *x != '.');
+
+    edges_front && edges_back && filled
+}
+
+fn count(
+    memo: &mut HashMap<(usize, usize), usize>,
+    sequence: &[char],
+    groups: &[usize],
+    ptr: usize,
+) -> usize {
+    match groups.split_first() {
+        None => !sequence.iter().skip(ptr).any(|c| *c == '#') as usize,
+        Some((group, r_groups)) => {
+            let remaining = r_groups.iter().sum();
+            let mut total = 0;
+
+            for idx in ptr..(sequence.len() - group - remaining + 1) {
+                if is_valid(sequence, idx, *group) {
+                    let next = idx + *group + 1;
+                    match memo.get(&(remaining, next)) {
+                        Some(m) => total += m,
+                        None => {
+                            let count = count(memo, sequence, r_groups, next);
+                            memo.insert((remaining, next), count);
+                            total += count
+                        }
+                    }
+                }
+
+                if sequence[idx] == '#' {
+                    break;
+                }
+            }
+            total
+        }
+    }
+}
+
+fn parse_line(line: &str) -> (Vec<char>, Vec<usize>) {
+    let (str_seq, str_grp) = line.split_once(' ').unwrap();
+    let sequence = str_seq.chars().collect();
+    let groups = str_grp.split(',').filter_map(|x| x.parse().ok()).collect();
+
+    (sequence, groups)
+}
+
+fn unfold(sequence: Vec<char>, groups: Vec<usize>, n: usize) -> (Vec<char>, Vec<usize>) {
+    let seq_len = sequence.len();
+    let grp_len = groups.len();
+
+    let new_sequence = sequence
+        .into_iter()
+        .chain(once('?'))
+        .cycle()
+        .take(seq_len * n + n - 1)
+        .collect();
+    let new_groups = groups.into_iter().cycle().take(grp_len * n).collect();
+
+    (new_sequence, new_groups)
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    Some(
+        input
+            .lines()
+            .map(parse_line)
+            .map(|(sequence, groups)| count(&mut HashMap::new(), &sequence, &groups, 0))
+            .sum(),
+    )
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    Some(
+        input
+            .lines()
+            .map(parse_line)
+            .map(|(sequence, groups)| unfold(sequence, groups, 5))
+            .map(|(sequence, groups)| count(&mut HashMap::new(), &sequence, &groups, 0))
+            .sum(),
+    )
+}
+
+aoc::solution!(12);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 12)),
+            Some(21)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 12)),
+            Some(525152)
+        );
+    }
+}

src/bin/13.rs

@@ -0,0 +1,64 @@
+fn mirror_h(shape: &[Vec<char>], smudges: usize) -> Option<usize> {
+    (1..shape.len()).find(|&i| {
+        shape
+            .iter()
+            .skip(i)
+            .zip(shape.iter().take(i).rev())
+            .map(|(x, y)| {
+                x.iter()
+                    .zip(y.iter())
+                    .map(|(xx, yy)| (xx != yy) as usize)
+                    .sum::<usize>()
+            })
+            .sum::<usize>()
+            == smudges
+    })
+}
+
+fn mirror_v(shape: &[Vec<char>], smudges: usize) -> Option<usize> {
+    let shape: Vec<Vec<char>> = (0..shape[0].len())
+        .map(|col| (0..shape.len()).map(|row| shape[row][col]).collect())
+        .collect();
+
+    mirror_h(&shape, smudges)
+}
+
+fn solve(input: &str, smudges: usize) -> usize {
+    input
+        .split("\n\n")
+        .map(|x| x.lines().map(|line| line.chars().collect()).collect())
+        .map(|shape: Vec<Vec<char>>| {
+            mirror_v(&shape, smudges).unwrap_or_default()
+                + mirror_h(&shape, smudges).unwrap_or_default() * 100
+        })
+        .sum()
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    Some(solve(input, 0))
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    Some(solve(input, 1))
+}
+
+aoc::solution!(13);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 13)),
+            Some(405)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 13)),
+            Some(400)
+        );
+    }
+}

src/bin/14.rs

@@ -0,0 +1,115 @@
+use std::{collections::HashMap, iter::once};
+
+enum Tilt {
+    North,
+    West,
+    South,
+    East,
+}
+
+fn get_load(floor: &[Vec<char>]) -> usize {
+    floor
+        .iter()
+        .enumerate()
+        .flat_map(|(i, x)| x.iter().map(move |y| (i, y)))
+        .filter(|x| *x.1 == 'O')
+        .map(|x| floor.len() - x.0)
+        .sum()
+}
+
+fn swap<T: Copy>(floor: &mut [Vec<T>], from: (usize, usize), to: (usize, usize)) {
+    let a = floor[from.0][from.1];
+    let b = floor[to.0][to.1];
+    floor[from.0][from.1] = b;
+    floor[to.0][to.1] = a;
+}
+
+fn tilt(floor: &mut [Vec<char>], tilt: Tilt) {
+    let (inner, outer) = match tilt {
+        Tilt::North | Tilt::South => (floor[0].len(), floor.len()),
+        Tilt::West | Tilt::East => (floor.len(), floor[0].len()),
+    };
+    let inx_n = |(i, j)| (j, i);
+    let inx_s = |(i, j)| (inner - 1 - j, i);
+    let inx_w = |(i, j)| (i, j);
+    let inx_e = |(i, j)| (i, inner - 1 - j);
+    for i in 0..outer {
+        let mut ptr = 0;
+        for j in 0..inner {
+            let ((ii, jj), (pi, pj)) = match tilt {
+                Tilt::North => (inx_n((i, j)), inx_n((i, ptr))),
+                Tilt::South => (inx_s((i, j)), inx_s((i, ptr))),
+                Tilt::East => (inx_e((i, j)), inx_e((i, ptr))),
+                Tilt::West => (inx_w((i, j)), inx_w((i, ptr))),
+            };
+            match floor[ii][jj] {
+                'O' => {
+                    swap(floor, (ii, jj), (pi, pj));
+                    ptr += 1;
+                }
+                '#' => ptr = j + 1,
+                _ => (),
+            }
+        }
+    }
+}
+
+fn tilt_cycle(floor: &mut [Vec<char>]) {
+    use Tilt::*;
+    tilt(floor, North);
+    tilt(floor, West);
+    tilt(floor, South);
+    tilt(floor, East);
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let mut f: Vec<Vec<_>> = input.lines().map(|x| x.chars().collect()).collect();
+    tilt(&mut f, Tilt::North);
+    Some(get_load(&f))
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    let mut f: Vec<Vec<_>> = input.lines().map(|x| x.chars().collect()).collect();
+    let mut memo: HashMap<String, usize> = HashMap::new();
+
+    for i in 1.. {
+        tilt_cycle(&mut f);
+        let repr = f
+            .iter()
+            .flat_map(|x| x.iter().chain(once(&'\n')))
+            .collect::<String>();
+
+        if let Some(ii) = memo.insert(repr, i) {
+            let m = i - ii;
+            let shift = (1_000_000_000 - ii) % m;
+
+            for _ in 0..shift {
+                tilt_cycle(&mut f);
+            }
+            break;
+        }
+    }
+
+    Some(get_load(&f))
+}
+
+aoc::solution!(14);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 14)),
+            Some(136)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 14)),
+            Some(64)
+        );
+    }
+}

src/bin/15.rs

@@ -0,0 +1,68 @@
+fn hash(s: &str) -> usize {
+    let mut total = 0;
+    for c in s.chars().map(|x| x as usize) {
+        total += c;
+        total *= 17;
+        total %= 256;
+    }
+    total
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    Some(input.lines().flat_map(|x| x.split(',')).map(hash).sum())
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    let mut map = vec![Vec::<(&str, usize)>::new(); 256];
+
+    for instruction in input.lines().flat_map(|x| x.split(',')) {
+        let (label, n) = instruction.split_once(|x| x == '-' || x == '=').unwrap();
+        let hash = hash(label);
+        let indexed_map = map.get_mut(hash).unwrap();
+
+        if instruction.contains('-') {
+            if let Some((i, _)) = indexed_map.iter().enumerate().find(|(_, &x)| x.0 == label) {
+                indexed_map.remove(i);
+            }
+        } else {
+            let nbr = n.parse().unwrap();
+            if let Some((i, _)) = indexed_map.iter().enumerate().find(|(_, &x)| x.0 == label) {
+                indexed_map[i] = (label, nbr);
+            } else {
+                indexed_map.push((label, nbr))
+            }
+        }
+    }
+
+    Some(
+        map.into_iter()
+            .enumerate()
+            .flat_map(|(i, x)| {
+                x.into_iter()
+                    .enumerate()
+                    .map(move |(j, y)| (i + 1) * (j + 1) * y.1)
+            })
+            .sum(),
+    )
+}
+
+aoc::solution!(15);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 15)),
+            Some(1320)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 15)),
+            Some(145)
+        );
+    }
+}

src/bin/16.rs

@@ -0,0 +1,173 @@
+use std::collections::HashSet;
+
+#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
+enum Direction {
+    Up,
+    Down,
+    Left,
+    Right,
+}
+
+impl Direction {
+    fn next(&self, (y, x): (usize, usize)) -> (usize, usize) {
+        use Direction::*;
+        match self {
+            Up => (y.checked_sub(1).unwrap_or(usize::MAX), x),
+            Down => (y + 1, x),
+            Left => (y, x.checked_sub(1).unwrap_or(usize::MAX)),
+            Right => (y, x + 1),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Mirror {
+    Vertical,
+    Horizontal,
+    EvenSymmetric,
+    OddSymmetric,
+}
+
+struct ParseMirrorError;
+
+impl TryFrom<u8> for Mirror {
+    type Error = ParseMirrorError;
+    fn try_from(value: u8) -> Result<Self, Self::Error> {
+        Ok(match value {
+            b'|' => Self::Vertical,
+            b'-' => Self::Horizontal,
+            b'\\' => Self::EvenSymmetric,
+            b'/' => Self::OddSymmetric,
+            _ => return Err(ParseMirrorError),
+        })
+    }
+}
+
+impl Mirror {
+    fn bounce(&self, d: &Direction) -> (Direction, Option<Direction>) {
+        use Direction::*;
+        use Mirror::*;
+
+        match self {
+            Vertical => match d {
+                Up | Down => (*d, None),
+                Left | Right => (Up, Some(Down)),
+            },
+            Horizontal => match d {
+                Up | Down => (Left, Some(Right)),
+                Left | Right => (*d, None),
+            },
+            EvenSymmetric => (
+                match d {
+                    Up => Left,
+                    Down => Right,
+                    Left => Up,
+                    Right => Down,
+                },
+                None,
+            ),
+            OddSymmetric => (
+                match d {
+                    Up => Right,
+                    Down => Left,
+                    Left => Down,
+                    Right => Up,
+                },
+                None,
+            ),
+        }
+    }
+}
+
+fn solve_with_start(layout: &[Vec<Option<Mirror>>], start: (usize, usize, Direction)) -> usize {
+    let mut queue = vec![start];
+    let mut visited = HashSet::new();
+
+    while let Some((y, x, d)) = queue.pop() {
+        let point = layout.get(y).and_then(|row| row.get(x));
+
+        if point.is_none() {
+            continue;
+        }
+
+        if !visited.insert((y, x, d)) {
+            continue;
+        }
+
+        if let Some(Some(m)) = point {
+            let (new_d, opt_new_d) = m.bounce(&d);
+            let (ny, nx) = new_d.next((y, x));
+            queue.push((ny, nx, new_d));
+
+            if let Some(od) = opt_new_d {
+                let (ony, onx) = od.next((y, x));
+                queue.push((ony, onx, od));
+            }
+        } else {
+            let (ny, nx) = d.next((y, x));
+            queue.push((ny, nx, d));
+        }
+    }
+
+    HashSet::<(usize, usize)>::from_iter(visited.into_iter().map(|(y, x, _)| (y, x))).len()
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let layout: Vec<Vec<_>> = input
+        .lines()
+        .map(|x| x.as_bytes().iter().map(|&x| x.try_into().ok()).collect())
+        .collect();
+
+    Some(solve_with_start(&layout, (0, 0, Direction::Right)))
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    let layout: Vec<Vec<_>> = input
+        .lines()
+        .map(|x| x.as_bytes().iter().map(|&x| x.try_into().ok()).collect())
+        .collect();
+
+    let h = layout.len();
+    let w = layout[0].len();
+
+    let mut scores = Vec::with_capacity(2 * (h + w) + 1);
+
+    for hh in 0..h {
+        let left = solve_with_start(&layout, (hh, 0, Direction::Right));
+        let right = solve_with_start(&layout, (hh, w - 1, Direction::Left));
+
+        scores.push(left);
+        scores.push(right);
+    }
+
+    for ww in 0..w {
+        let downward = solve_with_start(&layout, (0, ww, Direction::Down));
+        let upward = solve_with_start(&layout, (h - 1, ww, Direction::Up));
+
+        scores.push(downward);
+        scores.push(upward);
+    }
+
+    scores.into_iter().max()
+}
+
+aoc::solution!(16);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 16)),
+            Some(46)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 16)),
+            Some(51)
+        );
+    }
+}

src/bin/17.rs

@@ -0,0 +1,192 @@
+use std::{
+    collections::{BinaryHeap, HashMap},
+    ops::Neg,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+enum Direction {
+    Up,
+    Down,
+    Left,
+    Right,
+}
+
+impl Direction {
+    const ALL: [Direction; 4] = [
+        Direction::Up,
+        Direction::Down,
+        Direction::Left,
+        Direction::Right,
+    ];
+}
+
+impl Neg for Direction {
+    type Output = Self;
+    fn neg(self) -> Self::Output {
+        use Direction::*;
+        match self {
+            Up => Down,
+            Down => Up,
+            Left => Right,
+            Right => Left,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+struct State {
+    heat: usize,
+    position: (usize, usize),
+    direction: Direction,
+    steps: usize,
+}
+
+impl PartialOrd for State {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for State {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        other
+            .heat
+            .cmp(&self.heat)
+            .then_with(|| self.position.cmp(&other.position))
+    }
+}
+
+fn find_path(
+    grid: &[Vec<usize>],
+    start: (usize, usize),
+    target: (usize, usize),
+    min_steps: usize,
+    max_steps: usize,
+) -> Option<usize> {
+    let valid_indexing = |y: usize, x: usize| grid.get(y).and_then(|row| row.get(x)).is_some();
+
+    let mut heap = BinaryHeap::new();
+    heap.push(State {
+        heat: 0,
+        position: (0, 0),
+        direction: Direction::Right,
+        steps: 0,
+    });
+
+    let mut heatmap = HashMap::new();
+    heatmap.insert((start, Direction::Down, 0), 0);
+    heatmap.insert((start, Direction::Up, 0), 0);
+
+    while let Some(State {
+        heat,
+        position,
+        direction,
+        steps,
+    }) = heap.pop()
+    {
+        if position == target {
+            return Some(heat);
+        }
+
+        if *heatmap
+            .get(&(position, direction, steps))
+            .unwrap_or(&usize::MAX)
+            < heat
+        {
+            continue;
+        }
+
+        let (y, x) = position;
+        for d in Direction::ALL.iter().filter(|&x| *x != -direction) {
+            if steps < min_steps && *d != direction {
+                continue;
+            }
+
+            let (ny, nx) = match d {
+                Direction::Up => (y.wrapping_sub(1), x),
+                Direction::Down => (y + 1, x),
+                Direction::Left => (y, x.wrapping_sub(1)),
+                Direction::Right => (y, x + 1),
+            };
+
+            if !valid_indexing(ny, nx) {
+                continue;
+            }
+
+            let new_steps = if *d == direction { steps + 1 } else { 1 };
+
+            if new_steps > max_steps {
+                continue;
+            }
+
+            let state = State {
+                heat: heat + grid[ny][nx],
+                position: (ny, nx),
+                direction: *d,
+                steps: new_steps,
+            };
+
+            if *heatmap
+                .get(&((ny, nx), *d, new_steps))
+                .unwrap_or(&usize::MAX)
+                > state.heat
+            {
+                heatmap.insert(((ny, nx), *d, new_steps), state.heat);
+                heap.push(state);
+            }
+        }
+    }
+
+    None
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let grid: Vec<Vec<_>> = input
+        .lines()
+        .map(|x| {
+            x.chars()
+                .filter_map(|x| x.to_digit(10).map(|x| x as usize))
+                .collect()
+        })
+        .collect();
+
+    let target = (grid.len() - 1, grid[0].len() - 1);
+
+    find_path(&grid, (0, 0), target, 0, 3)
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    let grid: Vec<Vec<_>> = input
+        .lines()
+        .map(|x| {
+            x.chars()
+                .filter_map(|x| x.to_digit(10).map(|x| x as usize))
+                .collect()
+        })
+        .collect();
+
+    let target = (grid.len() - 1, grid[0].len() - 1);
+
+    find_path(&grid, (0, 0), target, 4, 10)
+}
+
+aoc::solution!(17);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 17)),
+            Some(102)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 17)),
+            Some(94)
+        );
+    }
+}

src/bin/18.rs

@@ -0,0 +1,126 @@
+use std::str::FromStr;
+
+#[derive(Debug, Clone, Copy)]
+enum Direction {
+    Up,
+    Down,
+    Left,
+    Right,
+}
+
+#[derive(Debug)]
+struct ParseDirectionError;
+
+impl FromStr for Direction {
+    type Err = ParseDirectionError;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        use Direction::*;
+
+        Ok(match s {
+            "U" | "3" => Up,
+            "D" | "1" => Down,
+            "L" | "2" => Left,
+            "R" | "0" => Right,
+            _ => return Err(ParseDirectionError),
+        })
+    }
+}
+
+impl From<Direction> for (isize, isize) {
+    fn from(value: Direction) -> Self {
+        use Direction::*;
+        match value {
+            Up => (-1, 0),
+            Down => (1, 0),
+            Left => (0, -1),
+            Right => (0, 1),
+        }
+    }
+}
+
+fn get_area(border: &[(isize, isize)], border_length: isize) -> isize {
+    // get area with shoelace formula (trapezoid variant)
+    // https://en.wikipedia.org/wiki/Shoelace_formula
+    let mut shoelace: isize = 0;
+    for n in 0..border.len() {
+        let (y1, x1) = border[n];
+        let (y2, x2) = border[(n + 1) % border.len()];
+        shoelace += (y1 + y2) * (x1 - x2);
+    }
+    let area = shoelace / 2;
+
+    // get interior by inverting pick's theorem formula
+    // https://en.wikipedia.org/wiki/Pick%27s_theorem
+    let interior = area + 1 - border_length / 2;
+    interior + border_length
+}
+
+fn get_border(instructions: &[(Direction, isize)]) -> (Vec<(isize, isize)>, isize) {
+    let mut border = Vec::new();
+    let mut border_length = 0;
+    let (mut sy, mut sx) = (0, 0);
+    border.push((sy, sx));
+
+    for (d, l) in instructions.iter().copied() {
+        let (dy, dx) = d.into();
+        (sy, sx) = (sy + l * dy, sx + l * dx);
+        border.push((sy, sx));
+        border_length += l;
+    }
+
+    border.pop();
+
+    (border, border_length)
+}
+
+pub fn part_one(input: &str) -> Option<isize> {
+    let instructions: Vec<(Direction, isize)> = input
+        .lines()
+        .map(|line| {
+            let [d, l, _] = line.splitn(3, ' ').collect::<Vec<_>>().try_into().unwrap();
+            (d.parse().unwrap(), l.parse::<isize>().unwrap())
+        })
+        .collect();
+
+    let (border, border_length) = get_border(&instructions);
+    Some(get_area(&border, border_length))
+}
+
+fn join_option_tuple<T, U>((a, b): (Option<T>, Option<U>)) -> Option<(T, U)> {
+    Some((a?, b?))
+}
+
+pub fn part_two(input: &str) -> Option<isize> {
+    let instructions: Vec<(Direction, isize)> = input
+        .lines()
+        .filter_map(|line| line.split_once(" (#"))
+        .filter_map(|(_, h)| h.strip_suffix(')'))
+        .map(|h| h.split_at(h.len() - 1))
+        .map(|(hex, dir)| (dir.parse().ok(), isize::from_str_radix(hex, 16).ok()))
+        .filter_map(join_option_tuple)
+        .collect();
+
+    let (border, border_length) = get_border(&instructions);
+    Some(get_area(&border, border_length))
+}
+
+aoc::solution!(18);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 18)),
+            Some(62)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 18)),
+            Some(952408144115)
+        );
+    }
+}

src/bin/19.rs

@@ -0,0 +1,387 @@
+use std::{
+    collections::HashMap,
+    ops::{Index, IndexMut},
+    str::FromStr,
+};
+
+#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
+enum Gear {
+    X,
+    M,
+    A,
+    S,
+}
+
+#[derive(Debug)]
+struct GearParseError;
+
+impl TryFrom<&str> for Gear {
+    type Error = GearParseError;
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        use Gear::*;
+        Ok(match value {
+            "x" => X,
+            "m" => M,
+            "a" => A,
+            "s" => S,
+            _ => return Err(GearParseError),
+        })
+    }
+}
+
+#[derive(Debug, Hash, PartialEq, Eq)]
+enum Comparator {
+    Lt,
+    Gt,
+}
+
+#[derive(Debug)]
+struct ComparatorParseError;
+
+impl TryFrom<char> for Comparator {
+    type Error = ComparatorParseError;
+    fn try_from(value: char) -> Result<Self, Self::Error> {
+        use Comparator::*;
+        Ok(match value {
+            '<' => Lt,
+            '>' => Gt,
+            _ => return Err(ComparatorParseError),
+        })
+    }
+}
+
+#[derive(Debug, Hash, PartialEq, Eq, Clone)]
+enum Resolver {
+    Accepted,
+    Rejected,
+    Delegated(String),
+}
+
+impl From<&str> for Resolver {
+    fn from(value: &str) -> Self {
+        use Resolver::*;
+        match value {
+            "A" => Accepted,
+            "R" => Rejected,
+            x => Delegated(x.to_string()),
+        }
+    }
+}
+
+#[derive(Debug, Hash, PartialEq, Eq)]
+struct Workflow {
+    workflows: Vec<WorkflowInner>,
+}
+
+#[derive(Debug)]
+struct ParseWorkflowError;
+
+impl TryFrom<&str> for Workflow {
+    type Error = ParseWorkflowError;
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        Ok(Self {
+            workflows: value.split(',').filter_map(|x| x.try_into().ok()).collect(),
+        })
+    }
+}
+
+#[derive(Debug, Hash, PartialEq, Eq)]
+enum WorkflowInner {
+    Resolver(Resolver),
+    Rule((Gear, Comparator, usize, Resolver)),
+}
+
+#[derive(Debug)]
+struct ParseWorkflowInnerError;
+
+impl TryFrom<&str> for WorkflowInner {
+    type Error = ParseWorkflowInnerError;
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        if !value.contains(':') {
+            return Ok(WorkflowInner::Resolver(value.into()));
+        }
+
+        let (rest, resolver) = value.split_once(':').unwrap();
+        let resolver = resolver.into();
+
+        let (gear, number) = rest.split_once(|x| x == '<' || x == '>').unwrap();
+        let gear = gear.try_into().map_err(|_| ParseWorkflowInnerError)?;
+        let number = number.parse().map_err(|_| ParseWorkflowInnerError)?;
+
+        let comparator = if value.contains('<') { '<' } else { '>' };
+        let comparator = comparator.try_into().map_err(|_| ParseWorkflowInnerError)?;
+
+        Ok(WorkflowInner::Rule((gear, comparator, number, resolver)))
+    }
+}
+
+#[derive(Debug)]
+struct Xmas {
+    x: usize,
+    m: usize,
+    a: usize,
+    s: usize,
+}
+
+#[derive(Debug)]
+struct ParseXmasError;
+
+impl FromStr for Xmas {
+    type Err = ParseXmasError;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let s = s.strip_prefix('{').ok_or(ParseXmasError)?;
+        let s = s.strip_suffix('}').ok_or(ParseXmasError)?;
+        let xmas: Vec<_> = s
+            .split(',')
+            .filter_map(|x| x.split_once('='))
+            .map(|x| x.1)
+            .filter_map(|x| x.parse().ok())
+            .collect();
+
+        Ok(Self {
+            x: xmas[0],
+            m: xmas[1],
+            a: xmas[2],
+            s: xmas[3],
+        })
+    }
+}
+
+impl Index<Gear> for Xmas {
+    type Output = usize;
+    fn index(&self, index: Gear) -> &Self::Output {
+        use Gear::*;
+        match index {
+            X => &self.x,
+            M => &self.m,
+            A => &self.a,
+            S => &self.s,
+        }
+    }
+}
+
+impl IndexMut<Gear> for Xmas {
+    fn index_mut(&mut self, index: Gear) -> &mut Self::Output {
+        use Gear::*;
+        match index {
+            X => &mut self.x,
+            M => &mut self.m,
+            A => &mut self.a,
+            S => &mut self.s,
+        }
+    }
+}
+
+impl Xmas {
+    fn sum(&self) -> usize {
+        self.x + self.m + self.a + self.s
+    }
+
+    fn apply(&self, workflow: &Workflow) -> Resolver {
+        for w in workflow.workflows.iter() {
+            match w {
+                WorkflowInner::Resolver(x) => {
+                    return x.clone();
+                }
+                WorkflowInner::Rule((g, c, n, r)) => {
+                    let is_match = match c {
+                        Comparator::Gt => self[*g] > *n,
+                        Comparator::Lt => self[*g] < *n,
+                    };
+                    if is_match {
+                        return r.clone();
+                    }
+                }
+            }
+        }
+
+        unreachable!()
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+struct XmasRange {
+    x: (usize, usize),
+    m: (usize, usize),
+    a: (usize, usize),
+    s: (usize, usize),
+}
+
+impl Index<Gear> for XmasRange {
+    type Output = (usize, usize);
+    fn index(&self, index: Gear) -> &Self::Output {
+        use Gear::*;
+        match index {
+            X => &self.x,
+            M => &self.m,
+            A => &self.a,
+            S => &self.s,
+        }
+    }
+}
+
+impl IndexMut<Gear> for XmasRange {
+    fn index_mut(&mut self, index: Gear) -> &mut Self::Output {
+        use Gear::*;
+        match index {
+            X => &mut self.x,
+            M => &mut self.m,
+            A => &mut self.a,
+            S => &mut self.s,
+        }
+    }
+}
+
+impl XmasRange {
+    fn size(&self) -> usize {
+        (self.x.1 - self.x.0 + 1)
+            * (self.m.1 - self.m.0 + 1)
+            * (self.a.1 - self.a.0 + 1)
+            * (self.s.1 - self.s.0 + 1)
+    }
+
+    fn divide(self, workflow: &Workflow) -> Vec<(Self, Resolver)> {
+        let mut processed = Vec::new();
+        let mut rest = vec![self];
+
+        for w in workflow.workflows.iter() {
+            let mut new_rest = Vec::new();
+
+            while let Some(xmas_range) = rest.pop() {
+                match w {
+                    WorkflowInner::Resolver(r) => processed.push((xmas_range, r.clone())),
+                    WorkflowInner::Rule((g, c, n, r)) => {
+                        let compare = |x: usize, y: usize| match c {
+                            Comparator::Gt => x > y,
+                            Comparator::Lt => x < y,
+                        };
+
+                        let mut min_ok = usize::MAX;
+                        let mut max_ok = usize::MIN;
+                        let mut min_e = usize::MAX;
+                        let mut max_e = usize::MIN;
+
+                        for i in xmas_range[*g].0..=xmas_range[*g].1 {
+                            if compare(i, *n) {
+                                max_ok = if max_ok < i { i } else { max_ok };
+                                min_ok = if min_ok > i { i } else { min_ok };
+                            } else {
+                                max_e = if max_e < i { i } else { max_e };
+                                min_e = if min_e > i { i } else { min_e };
+                            }
+                        }
+
+                        if min_e <= max_e {
+                            let mut r = xmas_range;
+                            r[*g] = (min_e, max_e);
+                            new_rest.push(r);
+                        }
+                        if min_ok <= max_ok {
+                            let mut p = xmas_range;
+                            p[*g] = (min_ok, max_ok);
+                            processed.push((p, r.clone()));
+                        }
+                    }
+                }
+            }
+
+            rest = new_rest;
+        }
+
+        processed
+    }
+}
+
+fn build_map(input: &str) -> HashMap<&str, Workflow> {
+    let mut map = HashMap::new();
+    for (s, w) in input
+        .split("\n\n")
+        .next()
+        .unwrap()
+        .lines()
+        .filter_map(|x| x.strip_suffix('}'))
+        .filter_map(|x| x.split_once('{'))
+        .filter_map(|(s, w)| w.try_into().ok().map(|x| (s, x)))
+    {
+        map.insert(s, w);
+    }
+
+    map
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let map = build_map(input);
+    let xmas_vec: Vec<Xmas> = input
+        .split("\n\n")
+        .nth(1)?
+        .lines()
+        .filter_map(|x| x.parse().ok())
+        .collect();
+
+    let mut total = 0;
+
+    'outer: for xmas in xmas_vec.into_iter() {
+        let mut workflow = &map["in"];
+        'apply: loop {
+            match xmas.apply(workflow) {
+                Resolver::Accepted => break 'apply,
+                Resolver::Rejected => continue 'outer,
+                Resolver::Delegated(x) => workflow = &map[x.as_str()],
+            }
+        }
+
+        total += xmas.sum();
+    }
+
+    Some(total)
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    let map = build_map(input);
+
+    let mut finished = Vec::new();
+    let mut stack = vec![(
+        XmasRange {
+            x: (1, 4000),
+            m: (1, 4000),
+            a: (1, 4000),
+            s: (1, 4000),
+        },
+        Resolver::Delegated("in".to_string()),
+    )];
+
+    while let Some((xmas_range, resolver)) = stack.pop() {
+        match resolver {
+            Resolver::Accepted => finished.push(xmas_range),
+            Resolver::Rejected => {
+                continue;
+            }
+            Resolver::Delegated(x) => {
+                let workflow = &map[x.as_str()];
+                stack.append(&mut xmas_range.divide(workflow))
+            }
+        }
+    }
+
+    Some(finished.iter().map(XmasRange::size).sum())
+}
+aoc::solution!(19);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 19)),
+            Some(19114)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 19)),
+            Some(167409079868000)
+        );
+    }
+}

src/bin/20.rs

@@ -0,0 +1,187 @@
+use std::{
+    collections::{HashMap, VecDeque},
+    mem::swap,
+    str::FromStr,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+enum Module {
+    Broadcaster,
+    FlipFlop(bool),
+    Conjuction,
+}
+
+#[derive(Debug)]
+struct ParseModuleError;
+
+impl FromStr for Module {
+    type Err = ParseModuleError;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(match s {
+            "%" => Module::FlipFlop(false),
+            "&" => Module::Conjuction,
+            _ => Module::Broadcaster,
+        })
+    }
+}
+
+#[derive(Debug)]
+struct Node {
+    index: usize,
+    module: Module,
+    inputs: Vec<usize>,
+    outputs: Vec<usize>,
+}
+
+fn parse_input(input: &str) -> Vec<Node> {
+    let mut nodes = Vec::new();
+    let mut mapper: HashMap<String, usize> = HashMap::new();
+
+    for line in input.lines() {
+        let (from, _) = line.split_once(" -> ").unwrap();
+        let (module, mut name) = from.split_at(1);
+        let module: Module = module.parse().unwrap();
+        if module == Module::Broadcaster {
+            name = from;
+        }
+
+        *mapper.entry(name.to_string()).or_default() = nodes.len();
+
+        let l = Node {
+            module,
+            index: nodes.len(),
+            inputs: Vec::new(),
+            outputs: Vec::new(),
+        };
+
+        nodes.push(l);
+    }
+
+    for line in input.lines() {
+        let (from, to) = line.split_once(" -> ").unwrap();
+        let (module, mut name) = from.split_at(1);
+        let module: Module = module.parse().unwrap();
+        if module == Module::Broadcaster {
+            name = from;
+        }
+
+        let index = mapper[name];
+        for destination in to.split(", ") {
+            let to_index = mapper[destination];
+            nodes[index].outputs.push(to_index);
+            nodes[to_index].inputs.push(index);
+        }
+    }
+
+    nodes
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let mut nodes = parse_input(input);
+
+    let mut graph = vec![vec![None; nodes.len()]; nodes.len()];
+
+    let mut highs = 0;
+    let mut lows = 0;
+
+    let broadcaster = nodes
+        .iter()
+        .find(|x| x.module == Module::Broadcaster)?
+        .index;
+
+    for _ in 0..1000 {
+        let mut stack = VecDeque::from([broadcaster]);
+        while !stack.is_empty() {
+            let mut new_stack = VecDeque::new();
+            let mut new_graph = graph.clone();
+
+            while let Some(index) = stack.pop_front() {
+                let node = &nodes[index];
+                let mut new_module = None;
+
+                match node.module {
+                    Module::Broadcaster => {
+                        for dest_index in node.outputs.iter() {
+                            new_graph[index][*dest_index] = Some(false);
+                            new_stack.push_back(*dest_index);
+                            lows += 1;
+                        }
+                    }
+                    Module::FlipFlop(high) => {
+                        let mut swapper = None;
+                        for in_index in nodes[index].inputs.iter() {
+                            let value = &mut graph[*in_index][index];
+                            if value.is_some() {
+                                debug_assert!(swapper.is_none());
+                                swap(&mut swapper, value);
+                            }
+                        }
+
+                        if !swapper.unwrap() {
+                            let signal = !high;
+
+                            for dest_index in nodes[index].outputs.iter() {
+                                new_graph[index][*dest_index] = Some(signal);
+                                new_stack.push_back(*dest_index);
+                                if signal {
+                                    highs += 1;
+                                } else {
+                                    lows += 1;
+                                }
+                            }
+
+                            new_module = Some(Module::FlipFlop(signal));
+                        }
+                    }
+                    Module::Conjuction => {
+                        let mut all = true;
+
+                        for in_index in nodes[index].inputs.iter() {
+                            let value = graph[*in_index][index];
+                            all &= value.unwrap_or(false);
+                        }
+
+                        for dest_index in nodes[index].outputs.iter() {
+                            new_graph[index][*dest_index] = Some(!all);
+                            new_stack.push_back(*dest_index);
+                            if !all {
+                                highs += 1;
+                            } else {
+                                lows += 1;
+                            }
+                        }
+                    }
+                }
+
+                let node = &mut nodes[index];
+                if let Some(module) = new_module {
+                    node.module = module;
+                }
+            }
+
+            stack = new_stack;
+            graph = new_graph;
+        }
+    }
+
+    Some(highs * lows)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    None
+}
+
+aoc::solution!(20);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(part_one(&aoc::template::read_file("examples", 20)), None);
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(part_two(&aoc::template::read_file("examples", 20)), None);
+    }
+}

src/lib.rs

@@ -2,3 +2,27 @@
 
 pub mod parsers;
 pub mod template;
+
+use std::mem::swap;
+
+pub fn lcm(first: usize, second: usize) -> usize {
+    first * second / gcd(first, second)
+}
+
+pub fn gcd(first: usize, second: usize) -> usize {
+    let mut max = first;
+    let mut min = second;
+    if min > max {
+        swap(&mut min, &mut max)
+    }
+
+    loop {
+        let res = max % min;
+        if res == 0 {
+            return min;
+        }
+
+        max = min;
+        min = res;
+    }
+}

src/template.rs

@@ -54,3 +54,14 @@ pub fn read_file(folder: &str, day: u8) -> String {
     let f = fs::read_to_string(filepath);
     f.expect("could not open input file").trim().to_string()
 }
+
+#[must_use]
+pub fn read_file_part(folder: &str, day: u8, part: u8) -> String {
+    let cwd = env::current_dir().unwrap();
+    let filepath = cwd
+        .join("data")
+        .join(folder)
+        .join(format!("{day:02}-{part}.txt"));
+    let f = fs::read_to_string(filepath);
+    f.expect("could not open input file").trim().to_string()
+}