day20 format

input/day20.txt

@@ -0,0 +1,109 @@
+                                   V         W   A S   Q         A     K
+                                   D         V   A H   R         Y     N
+  #################################.#########.###.#.###.#########.#####.#################################
+  #...........#.#...#...#.#...#...........#.....#.....#.........#.....#...............#.......#.........#
+  #.###.#.###.#.###.#.###.###.###.#.#.#####.###.#####.#######.#######.#######.#########.#.#####.#.#####.#
+  #.#...#.#.#...#...#...#.#.......#.#...#.....#.#.....#.......#.....#.#.#...#.#...#.#.#.#.#.#.#.#...#...#
+  #########.#.#####.#.###.###.#.#####.###.#.#######.###.#.#####.###.#.#.#.#.#.#.###.#.###.#.#.###.#####.#
+  #...#...#...#.#.#.....#.....#.....#...#.#.....#.....#.#...#.#...#.#.#...#...#.#...............#.#.#.#.#
+  #.#.###.###.#.#.#.#####.###.#.#.#######.#######.#####.#####.#.#.#.#.#.#######.#.#######.###.#.#.#.#.###
+  #.#.......................#.#.#...#.....#...#.....#.......#...#.#...#.............#.#.....#.#.#.....#.#
+  #.###.#####.#####.#####.#####.#########.#.###.###.###.#.#######.###########.###.###.###.#.#####.###.#.#
+  #.#...#.....#.#...#.....#.#...#...#.......#...#...#.#.#...#.#...#...#.....#.#.#.......#.#.#.......#...#
+  #.###########.###########.###.#.#######.#.###.###.#.###.###.#.###.#.#.###.#.#.#####.###.#.#.###.#######
+  #.#.#...#.#.#...#.#.............#.#...#.#...#.#.#.....#.#.#.......#.#.#.......#.#...#...#.#.#...#.....#
+  ###.#.###.#.#.###.#.###.###.#.#.#.#.###.#######.#.#.###.#.#.#.#.###.#.###.#.###.###.#.###.#####.#####.#
+  #...............#.#.#...#...#.#.....#...#...#...#.#.#.....#.#.#.#.#.#.#.#.#.......#.#.#.#.#.#...#.....#
+  #.#######.###.###.#########.#.#.#####.###.#####.###.#.###########.#.#.#.#.#.#.###.#####.###.###.###.###
+  #.#.#.#.#...#...#.#.#.......#.#.....#.......#...#.#.#.#.....#...#.#.#...#.#.#...#.#...#.....#.#.......#
+  ###.#.#.#####.#.#.#.#####.#########.#####.#####.#.#.#.###.#.###.#.#.#.#####.#.#######.###.###.#.#.#####
+  #.#.....#.#.#.#.....#.#.....#.......#...#...#.....#.#...#.#.#.....#.#...#...#.#.........#.#...#.#.#.#.#
+  #.#.#####.#.###.#####.#######.#######.#.###.#.#.#.#.###.#.#.#.###.#.#.###########.#.#####.###.#.###.#.#
+  #.....#.#.#.......#...#.#...#.......#.#...#.#.#.#.#.#.#...#.#...#...#...#...#.#...#.#.#.#.#.#.#...#.#.#
+  ###.###.#.#####.#####.#.#.#.#.#######.###.#.#.#.###.#.#####.###.#.###.###.###.#.###.#.#.#.#.#.#.###.#.#
+  #.....#...#.#...#...#.#.#.#.......#.....#...#.#.....#...#...#...#.#.#.#.#.#.......#...#...............#
+  ###.#.###.#.###.#.###.#.#######.#.###.#.#####.#######.#.#.#.#.###.#.#.#.#.###.###############.#.###.###
+  #...#.#.............#.#.#.......#...#.#.....#.....#...#...#.#...#.#.........#...#.....#.#.#.#.#...#.#.#
+  ###.#######.#.###.###.#.#####.#########.#####.#######.#######.#########.#######.###.###.#.#.###.#####.#
+  #.....#...#.#...#.#.....#    E         O     X       A       X         L      #.#...#...#.#.....#...#.#
+  #.#.###.#####.###.#####.#    N         C     E       Y       B         O      #.###.###.#.#.#####.###.#
+  #.#.....#.#.#.#...#.....#                                                     #.#.#.#.#.#.#...#...#...#
+  #.#.###.#.#.###.#.#.###.#                                                     #.#.#.#.#.#.#.#####.###.#
+  #.#.#.#...#.#...#...#...#                                                     #...............#.#.#.#.#
+  #####.#.#.#.###.#####.###                                                     #.#.#.#.#.#.###.#.#.#.#.#
+  #.#.....#.....#...#...#.#                                                     #.#.#.#.#.#.#...#.....#..UW
+  #.###.###.#.#.###.#.###.#                                                     #.###.#####.#.###.#.#.#.#
+DK......#.#.#.#.....#......VG                                                 EJ....#.#.....#.#...#.#...#
+  #####.#.###.###.###.#####                                                     #############.#.#.#####.#
+  #.....#...#.#...#...#....SY                                                   #...#...#...#...#.#.#...#
+  #########.#####.#####.###                                                     #.###.#####.#####.#.#####
+LO......#.....#.#.#...#...#                                                     #.........#.....#.#.....#
+  #.###.#####.#.###.#####.#                                                     #.#.###.###.###.###.###.#
+  #.#.....................#                                                     #.#.#.......#.#...#.#.#..XJ
+  #.#########.###.#########                                                     #.#####.#.###.###.#.#.###
+  #.#.#.....#...#.#.......#                                                   VD....#...#.#.......#.....#
+  #.#.###.#.#########.###.#                                                     #.#.###.#####.#####.###.#
+  #.#.#...#.........#...#..WV                                                   #.#.#...#.#...........#.#
+  ###.###.#####.###.###.###                                                     #####.###.###############
+XE........#...#.#.........#                                                   HX....#...#...#...#.....#.#
+  ###########.#############                                                     #.###.#####.#.###.###.#.#
+  #...#.#...#.........#...#                                                     #...#.#.#.#...#.....#.#..XB
+  #.#.#.#.#.#.###.###.###.#                                                     #.#####.#.###.###.#.#.#.#
+  #.#.....#...#.#.#.......#                                                     #.#.#.....#.#...#.#.#.#.#
+  #.#####.#####.#########.#                                                     #.#.#####.#.#.#.###.#.#.#
+  #.#.....#.......#.#.....#                                                     #.............#.....#...#
+  #.#########.###.#.#.#####                                                     ###.#.#.###.#.#######.###
+HX..#.#.#...#...#.#........OW                                                 XY..#.#.#.#...#.#.....#.#.#
+  ###.#.###.#.#############                                                     #.#######.#.###.###.###.#
+  #.#.....#.#.#.#.#.#...#.#                                                     #...#.....#.#...#...#...#
+  #.#.#####.#.#.#.#.#.#.#.#                                                     ###.###########.#.###.#.#
+  #...#.......#.....#.#....QR                                                   #.#.#.#.#.......#.#...#..AG
+  #.#.###.#.#######.#.#####                                                     #.#.#.#.#####.###.#.###.#
+WB..#.#...#...#.....#...#.#                                                     #...............#...#...#
+  ###.#.#.#######.#.###.#.#                                                     #.###.###.#.#######.#####
+  #.#...#.........#.....#.#                                                     #.#...#...#.#.#...#.#...#
+  #.#####################.#                                                     #########.###.###.###.#.#
+  #.......................#                                                     #...#...#.#.#...#.....#..DF
+  #.###.#.#.#####.#######.#                                                     ###.#.#.###.###.#.###.#.#
+EN..#...#.#...#...#.#...#.#                                                   ZH......#.............#.#.#
+  #######.#.#.#.###.#.#.#.#                                                     ###.###.#######.#.###.###
+  #...#.#.#.#.#.#.....#...#                                                   DF..#.#.....#.....#.#...#.#
+  ###.#.###.###.###.#.#####                                                     #.#####.###############.#
+  #.......#...#.#...#......KN                                                   #.#...#.#...#.....#.#...#
+  ###.#.#########.#########                                                     #.###.###.#######.#.#.#.#
+  #...#.#.#.#...#.#.......#                                                     #.....................#..GL
+  #.#.###.#.###.#####.#.###                                                     #########################
+  #.#...#.......#...#.#....AG                                                 WW..#.................#...#
+  #.#.#.#.#########.#.#.###                                                     #.#.###.###.#.#####.#.#.#
+ZH..#.#.#.#.#...#.....#.#.#                                                     #.....#...#.#...#.....#..RP
+  #####.#.#.#.###.#.#.#.#.#                                                     ###.###.#####.#.###.###.#
+  #...............#.#.#...#                                                     #...#.#...#...#.#.....#.#
+  ###.###.###.#.#.#.###.###      X       S     U   R     W           D G        ###.#.#.#.###.###.###.###
+  #...#.#...#.#.#.#.#...#.#      J       H     W   P     B           K L        #.#...#.#.#.#.#.#.#.....#
+  #####.#.###.#.###.#####.#######.#######.#####.###.#####.###########.#.#########.#.#.###.#.#.#.#####.#.#
+  #.#.....#.#.#...#...#.#.....#.#.....#...#.........#.........#.......#.........#...#...#.#.#.......#.#.#
+  #.###.#.#.#.#########.#.#####.#.#######.#####.###.#.#.#.#####.#####.#.###.#######.#####.#.###.###.#.#.#
+  #.#...#.#.......#...............#.#...#.....#.#.#.#.#.#.#...#.#...#.#.#...#...#.#.....#...#.....#.#.#.#
+  #.###.###.#########.#.#.#####.###.#.###.#.###.#.#####.#####.#.#.#.#######.###.#.###.#####.###.#########
+  #.......#.#.#.....#.#.#.#.............#.#.#.........#...#.....#.#.....#.........#...#.#...#...........#
+  #.###.###.#.#.#########.#####.#####.#####.###.#######.###.#.#.#.###.###.###.###.#####.#####.#.#.#####.#
+  #.#.....#.....#.....#...#.#.#.....#.#.......#.#.#...#...#.#.#...#...#.....#.#...........#.#.#.#.....#.#
+  #######.###.###.#######.#.#.#.#.#######.###.#.#.#.###.###########.#######.###########.#.#.#####.#####.#
+  #.......#...........#.#.#.....#.#.#...#.#...#.....#.......#.#...#.#...#.........#...#.#.....#.......#.#
+  #.#.#####.#.#.#.#.#.#.###.###.###.#.###.#.#.#.#######.#####.###.#.#.#.#.#########.###########.###.#####
+  #.#.#.#...#.#.#.#.#.#.#.#.#.#.........#.#.#.#.#.#.#.....#...#.......#.#...#.................#.#.......#
+  ###.#.###.###.###.#.#.#.###.#.#.###########.#.#.#.###.###.###.###.#######.#.#####.#.#.###.#######.#.###
+  #.......#...#...#.#.......#...#.#.......#...#.....#.#.....#.#.#.....#...........#.#.#...#.....#...#.#.#
+  ###.#####.#####.#.#.#.#####.#.#####.###.###.###.###.#.#####.#######.#.###.###.###.#######.###.###.###.#
+  #.....#...#.....#.#.#.#...#.#.....#.#...#.#.#.....#.....#.....#.....#.#...#...#.......#...#.....#.....#
+  ###.#####.###.###########.#####.#######.#.#.#.#.#####.#######.#.#####.#####.#######.###.#.#####.###.###
+  #...#.#.....#.#.#.......#.......#...#.#.....#.#.#...#.....#.#.......#...#.#.#.#.#.#...#.#.#.#.#...#...#
+  #####.#########.###.###.#####.#####.#.###.###.#####.#.#####.#######.#.###.###.#.#.#.#######.#.#########
+  #.#.......#.#.#.....#.#.............#.....#.#.....#.#...#.....#.....#.#...#.#.#.#.#...#...#...........#
+  #.###.#####.#.#.#####.#####.#.#.###.#.#####.#.#.#.#.#.###.#.#####.###.#.#.#.#.#.#.#####.#####.#####.###
+  #...............#.#.#.......#.#...#.#.......#.#.#...#.#...#.#.#.#...#...#.................#.......#...#
+  #.#.#.#.#.#####.#.#.#.#.#.#.#.#####.#.#.###.#.#####.#.#.###.#.#.###.#.###.#.#.###.#.#.#.#####.#########
+  #.#.#.#.#.#.....#.....#.#.#.#.#.....#.#.#...#.#.....#...#...#.......#.#...#.#.#...#.#.#...............#
+  ###############################.###.#####.#####.#.#######.###.#########.###############################
+                                 X   Z     V     O O       S   W         E
+                                 Y   Z     G     C W       Y   W         J

input/day20_example1.txt

@@ -0,0 +1,19 @@
+         A
+         A
+  #######.#########
+  #######.........#
+  #######.#######.#
+  #######.#######.#
+  #######.#######.#
+  #####  B    ###.#
+BC...##  C    ###.#
+  ##.##       ###.#
+  ##...DE  F  ###.#
+  #####    G  ###.#
+  #########.#####.#
+DE..#######...###.#
+  #.#########.###.#
+FG..#########.....#
+  ###########.#####
+             Z
+             Z

input/day20_example2.txt

@@ -0,0 +1,37 @@
+             Z L X W       C
+             Z P Q B       K
+  ###########.#.#.#.#######.###############
+  #...#.......#.#.......#.#.......#.#.#...#
+  ###.#.#.#.#.#.#.#.###.#.#.#######.#.#.###
+  #.#...#.#.#...#.#.#...#...#...#.#.......#
+  #.###.#######.###.###.#.###.###.#.#######
+  #...#.......#.#...#...#.............#...#
+  #.#########.#######.#.#######.#######.###
+  #...#.#    F       R I       Z    #.#.#.#
+  #.###.#    D       E C       H    #.#.#.#
+  #.#...#                           #...#.#
+  #.###.#                           #.###.#
+  #.#....OA                       WB..#.#..ZH
+  #.###.#                           #.#.#.#
+CJ......#                           #.....#
+  #######                           #######
+  #.#....CK                         #......IC
+  #.###.#                           #.###.#
+  #.....#                           #...#.#
+  ###.###                           #.#.#.#
+XF....#.#                         RF..#.#.#
+  #####.#                           #######
+  #......CJ                       NM..#...#
+  ###.#.#                           #.###.#
+RE....#.#                           #......RF
+  ###.###        X   X       L      #.#.#.#
+  #.....#        F   Q       P      #.#.#.#
+  ###.###########.###.#######.#########.###
+  #.....#...#.....#.......#...#.....#.#...#
+  #####.#.###.#######.#######.###.###.#.#.#
+  #.......#.......#.#.#.#.#...#...#...#.#.#
+  #####.###.#####.#.#.#.#.###.###.#.###.###
+  #.......#.....#.#...#...............#...#
+  #############.#.#.###.###################
+               A O F   N
+               A A D   M

src/main.rs

@@ -1,5 +1,7 @@
+extern crate core;
+
 mod tasks;
 
 fn main() {
-    tasks::day19::run();
+    tasks::day20::run();
 }

src/tasks/day19.rs

@@ -1,7 +1,8 @@
-use std::collections::HashMap;
 use super::day05::{IntCodeComputer, RAM};
 use itertools::Itertools;
+use std::collections::HashMap;
 
+#[allow(dead_code)]
 pub fn run() {
     let program = super::day05::load_ram("input/day19.txt");
     part1(&program, 50);
@@ -12,9 +13,7 @@ fn part1(program: &RAM, max_perimeter: i128) {
     let result = (0..max_perimeter)
         .flat_map(|x| {
             (0..max_perimeter)
-                .map(|y| {
+                .map(|y| read_coordinate(program, x, y))
-                    read_coordinate(program, x, y)
-                })
                 .collect_vec()
         })
         .filter(|v| *v)
@@ -27,13 +26,11 @@ const SHIP_SIZE: i128 = 100;
 
 fn part2(program: &RAM) {
     let mut map: HashMap<(i128, i128), bool> = HashMap::new();
-    (0..SHIP_SIZE)
+    (0..SHIP_SIZE).for_each(|x| {
-        .for_each(|x| {
+        (0..SHIP_SIZE).for_each(|y| {
-            (0..SHIP_SIZE)
+            map.insert((x, y), read_coordinate(program, x, y));
-                .for_each(|y| {
+        })
-                    map.insert((x, y), read_coordinate(program, x, y));
+    });
-                })
-        });
     for perimeter in 0.. {
         extend_horizon(program, &mut map, perimeter);
         if let Some((x, y)) = check_all_squares_starting_at(&map, perimeter) {
@@ -44,7 +41,10 @@ fn part2(program: &RAM) {
     }
 }
 
-fn check_all_squares_starting_at(map: &HashMap<(i128, i128), bool>, perimeter: i128) -> Option<(i128, i128)> {
+fn check_all_squares_starting_at(
+    map: &HashMap<(i128, i128), bool>,
+    perimeter: i128,
+) -> Option<(i128, i128)> {
     for i in 0..=perimeter {
         if let Some(point) = check_fits(map, i, perimeter) {
             return Some(point);
@@ -79,4 +79,4 @@ fn read_coordinate(program: &RAM, x: i128, y: i128) -> bool {
     let mut computer = IntCodeComputer::new(vec![x, y], program.clone());
     computer.run_until_end();
     *computer.get_output().first().unwrap() == 1
-}
+}

src/tasks/day20.rs

@@ -0,0 +1,363 @@
+use std::collections::{HashMap, HashSet, VecDeque};
+
+pub fn run() {
+    let input = std::fs::read_to_string("input/day20.txt").unwrap();
+    let maze = Maze::from(&input, PortalField::curried_factory);
+    let part1 = maze.shortest_path();
+    println!("Part 1: {}", part1);
+
+    let maze = Maze::from(&input, DimensionField::curried_factory);
+    let part1 = maze.shortest_path();
+    println!("Part 2: {}", part1);
+}
+
+type C = i32;
+type FieldFactory = Box<dyn Fn(&MapPoint) -> Box<dyn Field>>;
+
+#[derive(Hash, Eq, PartialEq, Copy, Clone, Debug)]
+struct MapPoint {
+    x: C,
+    y: C,
+}
+
+impl MapPoint {
+    fn of(x: C, y: C) -> Self {
+        MapPoint { x, y }
+    }
+
+    fn neighbors(self) -> Vec<MapPoint> {
+        vec![
+            MapPoint::of(self.x + 1, self.y),
+            MapPoint::of(self.x, self.y + 1),
+            MapPoint::of(self.x - 1, self.y),
+            MapPoint::of(self.x, self.y - 1),
+        ]
+    }
+}
+
+#[derive(Hash, Eq, PartialEq, Copy, Clone, Debug)]
+struct RealPoint {
+    x: C,
+    y: C,
+    level: usize,
+}
+
+impl RealPoint {
+    fn map_point(&self) -> MapPoint {
+        MapPoint {
+            x: self.x,
+            y: self.y,
+        }
+    }
+}
+
+impl RealPoint {
+    fn from(map_point: MapPoint, level: usize) -> Self {
+        RealPoint {
+            x: map_point.x,
+            y: map_point.y,
+            level,
+        }
+    }
+}
+
+trait Field {
+    fn neighbors(&self, at_level: usize) -> Vec<RealPoint>;
+    fn set_label_partner(&mut self, point: MapPoint);
+    fn set_neighbors(&mut self, neighbors: Vec<MapPoint>);
+    fn curried_factory(width: C, height: C) -> FieldFactory
+        where
+            Self: Sized;
+}
+
+struct PortalField {
+    neighbors: Vec<MapPoint>,
+}
+
+impl PortalField {
+    fn new() -> Self {
+        PortalField { neighbors: vec![] }
+    }
+}
+
+impl Field for PortalField {
+    fn neighbors(&self, _: usize) -> Vec<RealPoint> {
+        self.neighbors
+            .iter()
+            .map(|p| RealPoint::from(*p, 0))
+            .collect()
+    }
+
+    fn set_label_partner(&mut self, point: MapPoint) {
+        self.neighbors.push(point);
+    }
+
+    fn set_neighbors(&mut self, neighbors: Vec<MapPoint>) {
+        self.neighbors = neighbors;
+    }
+
+    fn curried_factory(_: C, _: C) -> FieldFactory {
+        Box::new(|_| Box::new(PortalField::new()))
+    }
+}
+
+struct DimensionField {
+    point: MapPoint,
+    neighbors: Vec<MapPoint>,
+    jump: Option<MapPoint>,
+    map_width: C,
+    map_height: C,
+}
+
+impl DimensionField {
+    fn is_inward(&self) -> bool {
+        let p = self.point;
+        p.x > 2 && p.x < self.map_width - 3 && p.y > 2 && p.y < self.map_height - 3
+    }
+}
+
+impl Field for DimensionField {
+    fn neighbors(&self, at_level: usize) -> Vec<RealPoint> {
+        let mut result: Vec<RealPoint> = self
+            .neighbors
+            .iter()
+            .map(|n| RealPoint::from(*n, at_level))
+            .collect();
+        if let Some(destination) = self.jump {
+            if self.is_inward() {
+                result.push(RealPoint::from(destination, at_level + 1));
+            } else if at_level > 0 {
+                result.push(RealPoint::from(destination, at_level - 1));
+            }
+        }
+
+        result
+    }
+
+    fn set_label_partner(&mut self, point: MapPoint) {
+        self.jump = Some(point);
+    }
+
+    fn set_neighbors(&mut self, neighbors: Vec<MapPoint>) {
+        self.neighbors = neighbors;
+    }
+
+    fn curried_factory(width: C, height: C) -> FieldFactory {
+        Box::new(move |point: &MapPoint| {
+            Box::new(Self {
+                point: *point,
+                neighbors: vec![],
+                jump: None,
+                map_width: width,
+                map_height: height,
+            })
+        })
+    }
+}
+
+type FieldMap = HashMap<MapPoint, Box<dyn Field>>;
+
+struct Maze {
+    map: FieldMap,
+    start: RealPoint,
+    finish: RealPoint,
+}
+
+impl Maze {
+    fn from(input: &String, factory: fn(C, C) -> FieldFactory) -> Self {
+        let (moc, width, height) = Self::map_of_chars(input);
+
+        let mut map = Self::create_map_of_free_spots(&moc, factory(width, height));
+        Self::add_physical_neighbors(&mut map);
+        let labels = Self::labels(&moc, width, height);
+        Self::process_labels(&mut map, &labels);
+        let start = labels["AA"][0];
+        let finish = labels["ZZ"][0];
+
+        Maze {
+            map,
+            start: RealPoint::from(start, 0),
+            finish: RealPoint::from(finish, 0),
+        }
+    }
+
+    fn shortest_path(&self) -> usize {
+        bfs(&self.map, self.start, self.finish)
+    }
+
+    fn process_labels(map: &mut FieldMap, labels: &HashMap<String, Vec<MapPoint>>) {
+        for (label, points) in labels {
+            if label == "AA" || label == "ZZ" {
+                continue;
+            }
+
+            map.get_mut(&points[0])
+                .unwrap()
+                .set_label_partner(points[1]);
+            map.get_mut(&points[1])
+                .unwrap()
+                .set_label_partner(points[0]);
+        }
+    }
+
+    fn labels(
+        moc: &HashMap<MapPoint, char>,
+        width: C,
+        height: C,
+    ) -> HashMap<String, Vec<MapPoint>> {
+        let horizontal: Vec<(String, MapPoint)> = (0..width - 2)
+            .into_iter()
+            .flat_map(|x| {
+                (0..height).into_iter().flat_map(move |y| {
+                    let mut triple = [
+                        moc[&MapPoint::of(x, y)],
+                        moc[&MapPoint::of(x + 1, y)],
+                        moc[&MapPoint::of(x + 2, y)],
+                    ];
+                    let left = Self::label(triple).map(|label| (label, MapPoint::of(x, y)));
+                    triple.reverse();
+                    let right = Self::label(triple).map(|label| (label, MapPoint::of(x + 2, y)));
+                    vec![left, right]
+                })
+            })
+            .flatten()
+            .collect();
+
+        let vertical: Vec<(String, MapPoint)> = (0..width)
+            .into_iter()
+            .flat_map(|x| {
+                (0..height - 2).into_iter().flat_map(move |y| {
+                    let mut triple = [
+                        moc[&MapPoint::of(x, y)],
+                        moc[&MapPoint::of(x, y + 1)],
+                        moc[&MapPoint::of(x, y + 2)],
+                    ];
+                    let left = Self::label(triple).map(|label| (label, MapPoint::of(x, y)));
+                    triple.reverse();
+                    let right = Self::label(triple).map(|label| (label, MapPoint::of(x, y + 2)));
+                    vec![left, right]
+                })
+            })
+            .flatten()
+            .collect();
+
+        let mut result = HashMap::new();
+        for (s, p) in horizontal.into_iter().chain(vertical.into_iter()) {
+            if !result.contains_key(&s) {
+                result.insert(s.clone(), vec![]);
+            }
+            result.get_mut(&s).unwrap().push(p);
+        }
+        result
+    }
+
+    fn label(chars: [char; 3]) -> Option<String> {
+        if chars[0] == '.' && chars[1].is_alphabetic() && chars[2].is_alphabetic() {
+            let label = if chars[1] < chars[2] {
+                format!("{}{}", chars[1], chars[2])
+            } else {
+                format!("{}{}", chars[2], chars[1])
+            };
+            Some(label)
+        } else {
+            None
+        }
+    }
+
+    fn add_physical_neighbors(map: &mut FieldMap) {
+        let points: HashSet<MapPoint> = map.keys().map(|p| *p).collect();
+        map.iter_mut().for_each(|(p, f)| {
+            let neighbors = p
+                .neighbors()
+                .into_iter()
+                .filter(|neighbor| points.contains(neighbor))
+                .collect();
+            f.set_neighbors(neighbors);
+        })
+    }
+
+    fn create_map_of_free_spots(
+        moc: &HashMap<MapPoint, char>,
+        field_factory: FieldFactory,
+    ) -> FieldMap {
+        moc.keys()
+            .filter(|p| moc[p] == '.')
+            .map(|p| (*p, field_factory(p)))
+            .collect()
+    }
+
+    fn map_of_chars(input: &String) -> (HashMap<MapPoint, char>, C, C) {
+        let mut map: HashMap<MapPoint, char> = input
+            .lines()
+            .enumerate()
+            .flat_map(|(y, line)| {
+                line.chars()
+                    .enumerate()
+                    .map(move |(x, c)| (MapPoint::of(x as C, y as C), c))
+            })
+            .collect();
+
+        let width = map.keys().map(|p| p.x).max().unwrap() + 1;
+        let height = map.keys().map(|p| p.y).max().unwrap() + 1;
+
+        for x in 0..width {
+            for y in 0..height {
+                if !map.contains_key(&MapPoint::of(x, y)) {
+                    map.insert(MapPoint::of(x, y), ' ');
+                }
+            }
+        }
+        (map, width, height)
+    }
+}
+
+fn bfs(map: &FieldMap, start: RealPoint, finish: RealPoint) -> usize {
+    let mut open: VecDeque<(RealPoint, usize)> = VecDeque::new();
+    let mut seen: HashSet<RealPoint> = HashSet::new();
+
+    open.push_back((start, 0));
+    seen.insert(start);
+
+    while let Some((p, d)) = open.pop_front() {
+        if p == finish {
+            return d;
+        }
+
+        for neighbor in map[&p.map_point()].neighbors(p.level) {
+            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::{DimensionField, Field, Maze, PortalField};
+
+    #[test]
+    fn example_part1() {
+        let input = std::fs::read_to_string("input/day20_example1.txt").unwrap();
+        let maze = Maze::from(&input, PortalField::curried_factory);
+        assert_eq!(maze.shortest_path(), 23);
+    }
+
+    #[test]
+    fn example_part2() {
+        let input = std::fs::read_to_string("input/day20_example2.txt").unwrap();
+        let maze = Maze::from(&input, DimensionField::curried_factory);
+        assert_eq!(maze.shortest_path(), 396);
+    }
+
+    #[test]
+    fn result() {
+        let input = std::fs::read_to_string("input/day20.txt").unwrap();
+        let maze = Maze::from(&input, PortalField::curried_factory);
+        assert_eq!(maze.shortest_path(), 454);
+
+        let maze = Maze::from(&input, DimensionField::curried_factory);
+        assert_eq!(maze.shortest_path(), 5744);
+    }
+}

src/tasks/mod.rs

@@ -16,6 +16,7 @@ pub mod day16;
 pub mod day17;
 pub mod day18;
 pub mod day19;
+pub mod day20;
 pub mod day21;
 #[allow(dead_code)]
 pub mod day22;