Day 03

2022/.gitignore

@@ -18,3 +18,4 @@ target/
 # @see https://old.reddit.com/r/adventofcode/comments/k99rod/sharing_input_data_were_we_requested_not_to/gf2ukkf/?context=3
 /src/inputs
 !/src/inputs/.keep
+puzzle.md

2022/src/bin/03.rs

@@ -0,0 +1,76 @@
+use advent_of_code::helpers::parse_input;
+use std::collections::HashSet;
+
+static PRIORITY_CHARS: &str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+fn get_prio(c: char) -> u32 {
+    let i = PRIORITY_CHARS.chars().position(|cc| cc == c).unwrap();
+    i as u32 + 1
+}
+
+fn get_comps(row: &str) -> (HashSet<char>, HashSet<char>) {
+    let (top, bot) = row.split_at(row.len() / 2);
+    (
+        HashSet::from_iter(top.chars()),
+        HashSet::from_iter(bot.chars()),
+    )
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let comps = parse_input(input, get_comps);
+    let intersections = comps.iter().map(|(t, b)| t.intersection(b));
+    let priorities = intersections.map(|inters| inters.map(|c| get_prio(*c)));
+    let sums: Vec<u32> = priorities.map(|inters| inters.sum()).collect();
+
+    let sum: u32 = sums.iter().sum();
+
+    Some(sum)
+}
+
+fn find_badge(group: &[&str]) -> char {
+    let group_sets: Vec<HashSet<char>> = group
+        .iter()
+        .map(|s| HashSet::from_iter(s.chars()))
+        .collect();
+
+    let mut badges: HashSet<char> = group_sets[0]
+        .intersection(&group_sets[1]) // cringe
+        .copied()
+        .collect();
+    badges = badges.intersection(&group_sets[2]).copied().collect();
+
+    *badges.iter().next().unwrap()
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let lines: Vec<&str> = input.lines().collect();
+    let groups = lines.chunks(3);
+
+    let prios: Vec<u32> = groups.map(|group| get_prio(find_badge(group))).collect();
+
+    let sum: u32 = prios.iter().sum();
+    Some(sum)
+}
+
+fn main() {
+    let input = &advent_of_code::read_file("inputs", 3);
+    advent_of_code::solve!(1, part_one, input);
+    advent_of_code::solve!(2, part_two, input);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let input = advent_of_code::read_file("examples", 3);
+        assert_eq!(part_one(&input), Some(157));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let input = advent_of_code::read_file("examples", 3);
+        assert_eq!(part_two(&input), Some(70));
+    }
+}

2022/src/examples/03.txt

@@ -0,0 +1,6 @@
+vJrwpWtwJgWrhcsFMMfFFhFp
+jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL
+PmmdzqPrVvPwwTWBwg
+wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
+ttgJtRGJQctTZtZT
+CrZsJsPPZsGzwwsLwLmpwMDw

2022/src/helpers.rs

@@ -3,6 +3,8 @@
  * Example import from this file: `use advent_of_code::helpers::example_fn;`.
  */
 
+use std::collections::HashSet;
+
 pub fn parse_input<T>(input: &str, cons: fn(&str) -> T) -> Vec<T>
 where
     Vec<T>: FromIterator<T>,