add day 8 through 10

day09/Cargo.lock

@@ -0,0 +1,25 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day09"
+version = "0.1.0"
+dependencies = [
+ "itertools",
+]
+
+[[package]]
+name = "either"
+version = "1.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "91622ff5e7162018101f2fea40d6ebf4a78bbe5a49736a2020649edf9693679e"
+
+[[package]]
+name = "itertools"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b4baf93f58d4425749ca49a51c50ebab072c5df6994d08fed93541c331481dc"
+dependencies = [
+ "either",
+]

day09/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "day09"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+itertools = "0.15.0"

day09/input.txt

@@ -0,0 +1,28 @@
+AlphaCentauri to Snowdin = 66
+AlphaCentauri to Tambi = 28
+AlphaCentauri to Faerun = 60
+AlphaCentauri to Norrath = 34
+AlphaCentauri to Straylight = 34
+AlphaCentauri to Tristram = 3
+AlphaCentauri to Arbre = 108
+Snowdin to Tambi = 22
+Snowdin to Faerun = 12
+Snowdin to Norrath = 91
+Snowdin to Straylight = 121
+Snowdin to Tristram = 111
+Snowdin to Arbre = 71
+Tambi to Faerun = 39
+Tambi to Norrath = 113
+Tambi to Straylight = 130
+Tambi to Tristram = 35
+Tambi to Arbre = 40
+Faerun to Norrath = 63
+Faerun to Straylight = 21
+Faerun to Tristram = 57
+Faerun to Arbre = 83
+Norrath to Straylight = 9
+Norrath to Tristram = 50
+Norrath to Arbre = 60
+Straylight to Tristram = 27
+Straylight to Arbre = 81
+Tristram to Arbre = 90

day09/src/main.rs

@@ -0,0 +1,68 @@
+use std::collections::HashSet;
+
+use itertools::Itertools;
+
+fn main() {
+    let data = std::fs::read_to_string("input.txt").unwrap();
+    let legs: Vec<_> = data.lines().map(Leg::from_str).collect();
+
+    part1(&legs);
+}
+
+fn part1(legs: &[Leg]) {
+    let mut locations = HashSet::new();
+    for (s, e) in legs.iter().map(|l| (l.from.as_str(), l.to.as_str())) {
+        locations.insert(s);
+        locations.insert(e);
+    }
+
+    let length = locations.len();
+
+    let routes = locations.into_iter().permutations(length).collect_vec();
+
+    let mut sums = vec![];
+
+    for route in routes {
+        let sum: usize = route
+            .iter()
+            .tuple_windows()
+            .map(|(l, r)| find_length(legs, l, r))
+            .sum();
+        sums.push(sum);
+    }
+    sums.sort_unstable();
+    println!("{}\n{}", sums[0], sums.last().unwrap());
+}
+
+fn find_length(legs: &[Leg], a: &str, b: &str) -> usize {
+    for leg in legs {
+        if (leg.from == a || leg.to == a) && (leg.from == b || leg.to == b) {
+            return leg.distance;
+        }
+    }
+    unreachable!()
+}
+
+#[derive(Debug)]
+struct Leg {
+    pub from: String,
+    pub to: String,
+    pub distance: usize,
+}
+
+impl Leg {
+    fn new(from: String, to: String, distance: usize) -> Self {
+        Self { from, to, distance }
+    }
+
+    fn from_str(s: &str) -> Self {
+        let mut segments = s.split_whitespace();
+        let from = segments.next().unwrap().to_string();
+        let to = segments.nth(1).unwrap().to_string();
+        let distance = segments.next_back().unwrap().parse().unwrap();
+
+        Self::new(from, to, distance)
+    }
+}
+
+// https://adventofcode.com/2015/day/9