solution: day13

src/bin/13.rs

@@ -0,0 +1,97 @@
+use hashbrown::{HashMap, HashSet};
+use itertools::Itertools;
+use lazy_static::lazy_static;
+use regex::Regex;
+
+lazy_static! {
+    static ref RE: Regex = Regex::new(r#"(?P<person>\w+) would (?P<relation>\w{4}) (?P<amount>\d+) happiness units by sitting next to (?P<other>\w+)"#).unwrap();
+}
+
+#[derive(Debug, PartialEq, Hash)]
+struct Line {
+    person: String,
+    other: String,
+    amount: i32,
+}
+
+impl From<&str> for Line {
+    fn from(value: &str) -> Self {
+        let cap = RE.captures(value).unwrap();
+
+        let person = cap["person"].to_string();
+        let other = cap["other"].to_string();
+        let mut amount = cap["amount"].parse().unwrap();
+        if let "lose" = &cap["relation"] {
+            amount *= -1;
+        };
+
+        Line {
+            person,
+            other,
+            amount,
+        }
+    }
+}
+
+fn solve(input: &str, insert_myself: bool) -> u32 {
+    let mut map = HashMap::new();
+    let mut set = HashSet::new();
+    for line in input.split('\n') {
+        let parsed = Line::from(line);
+        map.insert(
+            (parsed.person.to_string(), parsed.other.to_string()),
+            parsed.amount,
+        );
+        set.insert(parsed.person.to_string());
+    }
+
+    if insert_myself {
+        for p in set.iter() {
+            map.insert((p.to_string(), "Matej".to_string()), 0);
+            map.insert(("Matej".to_string(), p.to_string()), 0);
+        }
+        set.insert("Matej".to_string());
+    }
+
+    set.iter()
+        .permutations(set.len())
+        .map(|x| {
+            x.iter()
+                .cycle()
+                .take(set.len() + 1)
+                .tuple_windows()
+                .map(|(a, b)| {
+                    map.get(&(a.to_string(), b.to_string())).unwrap()
+                        + map.get(&(b.to_string(), a.to_string())).unwrap()
+                })
+                .sum::<i32>()
+        })
+        .max()
+        .unwrap() as u32
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    Some(solve(input, false))
+}
+pub fn part_two(input: &str) -> Option<u32> {
+    Some(solve(input, true))
+}
+fn main() {
+    let input = &aoc::read_file("inputs", 13);
+    aoc::solve!(1, part_one, input);
+    aoc::solve!(2, part_two, input);
+}
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        let input = aoc::read_file("test_inputs", 13);
+        assert_eq!(part_one(&input.trim()), Some(330));
+    }
+    #[test]
+    fn test_part_two() {
+        let input = aoc::read_file("test_inputs", 13);
+        assert_eq!(part_two(&input.trim()), Some(286));
+    }
+}

src/test_inputs/13.txt

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+Alice would gain 54 happiness units by sitting next to Bob.
+Alice would lose 79 happiness units by sitting next to Carol.
+Alice would lose 2 happiness units by sitting next to David.
+Bob would gain 83 happiness units by sitting next to Alice.
+Bob would lose 7 happiness units by sitting next to Carol.
+Bob would lose 63 happiness units by sitting next to David.
+Carol would lose 62 happiness units by sitting next to Alice.
+Carol would gain 60 happiness units by sitting next to Bob.
+Carol would gain 55 happiness units by sitting next to David.
+David would gain 46 happiness units by sitting next to Alice.
+David would lose 7 happiness units by sitting next to Bob.
+David would gain 41 happiness units by sitting next to Carol.