day20 part 1

src/tasks/day20.rs

@@ -1,7 +1,11 @@
-use std::collections::{HashMap, HashSet};
-use std::fmt::format;
+use std::collections::{HashMap, HashSet, VecDeque};
 
-pub fn run() {}
+pub fn run() {
+    let input = std::fs::read_to_string("input/day20.txt").unwrap();
+    let maze = Maze::from(&input);
+    let part1 = maze.shortest_path();
+    println!("Part 1: {}", part1);
+}
 
 type C = i32;
 
@@ -27,23 +31,17 @@ impl Point {
 }
 
 struct Field {
-    point: Point,
     neighbors: Vec<Point>,
 }
 
 impl Field {
-    fn of(point: Point) -> Self {
-        Field {
-            point,
-            neighbors: vec![],
-        }
+    fn of() -> Self {
+        Field { neighbors: vec![] }
     }
 }
 
 pub struct Maze {
     map: HashMap<Point, Field>,
-    width: C,
-    height: C,
     start: Point,
     finish: Point,
 }
@@ -51,7 +49,6 @@ pub struct Maze {
 impl Maze {
     pub fn from(input: &String) -> Self {
         let (moc, width, height) = Self::map_of_chars(input);
-        println!("moc size {}, w {width}, h {height}", moc.len());
 
         let mut map = Self::create_map_of_free_spots(&moc);
         Self::add_physical_neighbors(&mut map);
@@ -60,15 +57,14 @@ impl Maze {
         let start = labels["AA"][0];
         let finish = labels["ZZ"][0];
 
-        Maze { map, width, height, start, finish }
+        Maze { map, start, finish }
     }
 
     pub fn shortest_path(&self) -> usize {
-        todo!()
+        bfs(&self.map, self.start, self.finish)
     }
 
     fn add_portals(map: &mut HashMap<Point, Field>, labels: &HashMap<String, Vec<Point>>) {
-        println!("{:?}", labels);
         for (label, points) in labels {
             if label == "AA" || label == "ZZ" {
                 continue;
@@ -84,7 +80,6 @@ impl Maze {
             .into_iter()
             .flat_map(|x| {
                 (0..height).into_iter().flat_map(move |y| {
-                    println!("{x} {y} h?");
                     let mut triple = [
                         moc[&Point::of(x, y)],
                         moc[&Point::of(x + 1, y)],
@@ -103,7 +98,6 @@ impl Maze {
             .into_iter()
             .flat_map(|x| {
                 (0..height - 2).into_iter().flat_map(move |y| {
-                    println!("{x} {y} v?");
                     let mut triple = [
                         moc[&Point::of(x, y)],
                         moc[&Point::of(x, y + 1)],
@@ -129,7 +123,6 @@ impl Maze {
     }
 
     fn label(chars: [char; 3]) -> Option<String> {
-        println!("{}{}{}", chars[0], chars[1], chars[2]);
         if chars[0] == '.' && chars[1].is_alphabetic() && chars[2].is_alphabetic() {
             let label = if chars[1] < chars[2] {
                 format!("{}{}", chars[1], chars[2])
@@ -157,7 +150,7 @@ impl Maze {
     fn create_map_of_free_spots(moc: &HashMap<Point, char>) -> HashMap<Point, Field> {
         moc.keys()
             .filter(|p| moc[p] == '.')
-            .map(|p| (*p, Field::of(*p)))
+            .map(|p| (*p, Field::of()))
             .collect()
     }
 
@@ -186,6 +179,27 @@ impl Maze {
     }
 }
 
+fn bfs(map: &HashMap<Point, Field>, start: Point, finish: Point) -> usize {
+    let mut open: VecDeque<(Point, usize)> = VecDeque::new();
+    let mut seen: HashSet<Point> = HashSet::new();
+
+    open.push_back((start, 0));
+
+    while let Some((p, d)) = open.pop_front() {
+        if p == finish {
+            return d;
+        }
+
+        for neighbor in &map[&p].neighbors {
+            if !seen.contains(neighbor) {
+                open.push_back((*neighbor, d + 1));
+            }
+            seen.insert(*neighbor);
+        }
+    }
+    panic!("no path found")
+}
+
 #[cfg(test)]
 mod test {
     use crate::tasks::day20::Maze;
@@ -196,4 +210,11 @@ mod test {
         let maze = Maze::from(&input);
         assert_eq!(maze.shortest_path(), 23);
     }
-}
+
+    #[test]
+    fn result() {
+        let input = std::fs::read_to_string("input/day20.txt").unwrap();
+        let maze = Maze::from(&input);
+        assert_eq!(maze.shortest_path(), 454);
+    }
+}