Small changes.

2015/09/src/main.rs

@@ -0,0 +1,125 @@
+#[macro_use] extern crate lazy_static;
+extern crate regex;
+
+use std::io::{self, Read};
+use std::collections::BTreeMap;
+
+use regex::Regex;
+
+
+type Map<'a> = BTreeMap<&'a str, BTreeMap<&'a str, i64>>;
+
+
+#[derive(Clone, Debug)]
+struct Route<'a> {
+    vec: Vec<&'a str>,
+    distance: i64
+}
+
+impl<'a> Route<'a> {
+    fn new() -> Route<'a> {
+        Route {
+            vec: Vec::new(),
+            distance: 0
+        }
+    }
+}
+
+
+fn process<'a>(input: &'a str) -> Route<'a> {
+    lazy_static! {
+        static ref RE: Regex = Regex::new(r"^([a-zA-Z]+) to ([a-zA-Z]+) = (\d+)$").unwrap();
+    }
+
+    let mut map: Map = BTreeMap::new();
+
+    for line in input.lines() {
+        let caps = RE.captures(&line).unwrap();
+
+        let a = caps.at(1).unwrap();
+        let b = caps.at(2).unwrap();
+
+        let distance = caps.at(3).unwrap().parse::<i64>().unwrap();
+
+        map.entry(a).or_insert(BTreeMap::new()).insert(b, distance);
+        map.entry(b).or_insert(BTreeMap::new()).insert(a, distance);
+    }
+
+    let mut routes = iterate(&map, None);
+
+    routes.sort_by_key(|x| x.distance);
+
+    routes.remove(0)
+}
+
+fn iterate<'a>(map: &Map<'a>, route: Option<Route<'a>>) -> Vec<Route<'a>> {
+    let mut routes = Vec::new();
+
+    if let Some(mut route) = route {
+        let prev = *route.vec.last().unwrap();
+
+        let mut end = true;
+
+        for (city, distance) in map.get(prev).unwrap().iter() {
+            if route.vec.contains(city) {
+                continue;
+            }
+
+            route.vec.push(*city);
+            route.distance += *distance;
+
+            {
+                let mut sub_routes = iterate(&map, Some(route.clone()));
+
+                routes.append(&mut sub_routes);
+            }
+
+            end = false;
+        }
+
+        if end {
+            routes.push(route);
+        }
+    } else {
+        for city in map.keys() {
+            let mut route = Route::new();
+
+            route.vec.push(*city);
+
+            {
+                let mut sub_routes = iterate(&map, Some(route));
+
+                routes.append(&mut sub_routes);
+            }
+        }
+    }
+
+    routes
+}
+
+fn main() {
+    let mut input = String::new();
+
+    io::stdin().read_to_string(&mut input).unwrap();
+
+    let result = process(&input);
+
+    println!("{:?}", result);
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::process;
+
+    #[test]
+    fn example_01() {
+        let input = "London to Dublin = 464\n\
+                     London to Belfast = 518\n\
+                     Dublin to Belfast = 141";
+
+        let result = process(input);
+
+        assert_eq!(605, result.distance);
+    }
+}