solution: day9

src/bin/09.rs

@@ -0,0 +1,53 @@
+use hashbrown::{HashMap, HashSet};
+use itertools::Itertools;
+
+fn get_all_distances(input: &str) -> Vec<u32> {
+    let mut distances = HashMap::new();
+    let mut cities = HashSet::new();
+
+    for line in input.trim().split('\n') {
+        let (a, b) = line.split(" = ").tuple_windows().next().unwrap();
+        let (x, y) = a.split(" to ").tuple_windows().next().unwrap();
+        distances.insert((x.to_string(), y.to_string()), b.parse::<u32>().unwrap());
+        distances.insert((y.to_string(), x.to_string()), b.parse::<u32>().unwrap());
+        cities.insert(x.to_string());
+        cities.insert(y.to_string());
+    }
+
+    cities
+        .iter()
+        .permutations(cities.len())
+        .map(|x| {
+            x.iter()
+                .tuple_windows()
+                .map(|(a, b)| distances.get(&(a.to_string(), b.to_string())).unwrap())
+                .sum()
+        })
+        .collect_vec()
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    get_all_distances(input).iter().min().copied()
+}
+pub fn part_two(input: &str) -> Option<u32> {
+    get_all_distances(input).iter().max().copied()
+}
+fn main() {
+    let input = &aoc::read_file("inputs", 9);
+    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", 9);
+        assert_eq!(part_one(&input), Some(605));
+    }
+    #[test]
+    fn test_part_two() {
+        let input = aoc::read_file("test_inputs", 9);
+        assert_eq!(part_two(&input), Some(982));
+    }
+}

src/test_inputs/09.txt

@@ -0,0 +1,3 @@
+London to Dublin = 464
+London to Belfast = 518
+Dublin to Belfast = 141