Advent 2015 Day 7, 8 & 9 Parts 1 & 2

advent_of_code_2015/src/day9/part1.rs

@@ -0,0 +1,55 @@
+use std::collections::{HashMap, HashSet};
+
+fn generate_routes(current: String, mut destinations: HashSet<String>) -> Vec<Vec<String>> {
+    destinations.remove(&current);
+    let mut routes = Vec::new();
+    
+    if destinations.is_empty() {
+        routes.push([current].to_vec());
+        return routes;
+    }
+
+    for destination in destinations.iter() {
+        routes.append(&mut generate_routes(destination.clone(), destinations.clone()));
+    }
+
+    for route in routes.iter_mut() {
+        route.push(current.clone());
+    }
+
+    routes
+}
+
+pub fn solve(input: &str) {
+    let mut distances: HashMap<String, HashMap<String, u64>> = HashMap::new();
+    
+    input.lines().for_each(|line| {
+        let (from, tail) = line.split_once(" to ").unwrap();
+        let (to, distance) = tail.split_once(" = ").unwrap();
+
+        distances.entry(from.into()).or_default().insert(to.to_string(), distance.parse().unwrap());
+        distances.entry(to.into()).or_default().insert(from.to_string(), distance.parse().unwrap());
+    });
+
+    let cities = distances.keys().cloned().collect::<HashSet<_>>();
+    let mut routes: Vec<Vec<String>> = Vec::new();
+
+    for city in cities.iter() {
+        routes.append(&mut generate_routes(city.clone(), cities.clone()));
+    }
+    
+    
+    let route_lengths = routes.iter().map(|route| {
+        let mut distance = 0u64;
+        for idx in 0..(route.len() - 1) {
+            distance += distances[&route[idx]][&route[idx + 1]];
+        }
+        distance
+    }).collect::<Vec<_>>();
+
+    // for (route, length) in routes.iter().zip(route_lengths) {
+    //     println!("route: {route:?}, distance: {length}");
+    // }
+
+    println!("shortest route: {}", route_lengths.iter().min().unwrap());
+}