day15 part1 movement

input/day15.txt

@@ -0,0 +1,9 @@
+#########
+#G..G..G#
+#.......#
+#.......#
+#G..E..G#
+#.......#
+#.......#
+#G..G..G#
+#########

src/main.rs

@@ -1,4 +1,4 @@
 fn main() {
-    // aoc_2018::tasks::day14::task1();
+    aoc_2018::tasks::day15::task1();
-    aoc_2018::tasks::day14::task2();
+    // aoc_2018::tasks::day15::task2();
 }

src/tasks/day15.rs

@@ -0,0 +1,370 @@
+use crate::utils;
+use std::collections::HashMap;
+use std::collections::HashSet;
+use std::collections::VecDeque;
+use std::fmt::Display;
+
+pub fn task1() {
+    let input = utils::read_file("input/day15.txt");
+    let mut game = Game::from_input(input.lines().collect());
+    println!("{}", game);
+    game.round();
+    println!("{}", game);
+    game.round();
+    println!("{}", game);
+    game.round();
+    println!("{}", game);
+    game.round();
+    println!("{}", game);
+}
+
+#[derive(Clone, PartialEq)]
+enum Tile {
+    Empty,
+    Wall,
+    Unit(WarriorType),
+}
+
+#[derive(Clone, Copy, PartialEq)]
+enum WarriorType {
+    Elve,
+    Goblin,
+}
+
+impl WarriorType {
+    fn enemy_type(&self) -> Self {
+        use self::WarriorType::*;
+        match self {
+            Elve => Goblin,
+            Goblin => Elve,
+        }
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+struct Position(usize, usize);
+
+impl Position {
+    fn neighbors(&self, width: usize, height: usize) -> Vec<Position> {
+        vec![
+            (self.0 as isize, self.1 as isize - 1),
+            (self.0 as isize - 1, self.1 as isize),
+            (self.0 as isize + 1, self.1 as isize),
+            (self.0 as isize, self.1 as isize + 1),
+        ]
+        .into_iter()
+        .filter(|p| p.0 > 0 && p.0 < width as isize - 1 && p.1 > 0 && p.1 < height as isize - 1)
+        .map(|it| Position(it.0 as usize, it.1 as usize))
+        .collect()
+    }
+}
+
+impl PartialOrd for Position {
+    fn partial_cmp(&self, other: &Self) -> std::option::Option<std::cmp::Ordering> {
+        if self.1 == other.1 {
+            Some(self.0.cmp(&other.0))
+        } else {
+            Some(self.1.cmp(&other.1))
+        }
+    }
+}
+
+impl Ord for Position {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        if self.1 == other.1 {
+            self.0.cmp(&other.0)
+        } else {
+            self.1.cmp(&other.1)
+        }
+    }
+}
+
+struct Warrior {
+    warrior_type: WarriorType,
+    position: Position,
+    health: i32,
+}
+
+struct Game {
+    units: Vec<Warrior>,
+    /// [x, y]
+    tiles: Vec<Vec<Tile>>,
+    width: usize,
+    height: usize,
+}
+
+impl Game {
+    fn closest_fighting_position(
+        &self,
+        from: Position,
+        target_type: WarriorType,
+    ) -> Option<Position> {
+        let mut map = Map::from_game(&self, from);
+
+        for unit in self.units.iter() {
+            if unit.warrior_type == target_type {
+                for neighbor in unit.position.neighbors(self.width, self.height) {
+                    if map.fields[neighbor.0][neighbor.1] == MapTile::Empty {
+                        map.fields[neighbor.0][neighbor.1] = MapTile::TargetNonOccupied;
+                    }
+                }
+            }
+        }
+
+        map.find_closest_target(from)
+    }
+
+    fn next_position(&self, from: Position, to: Position) -> Option<Position> {
+        if from == to {
+            return Some(from);
+        }
+        let input = vec![
+            (1, Position(from.0, from.1 - 1)),
+            (2, Position(from.0 - 1, from.1)),
+            (3, Position(from.0 + 1, from.1)),
+            (4, Position(from.0, from.1 + 1)),
+        ];
+        if let Some((_, best)) = input
+            .iter()
+            .filter_map(|(delta, start)| {
+                let map = Map::from_game(&self, *start);
+                if let Some(path) = map.shortest_path(*start, to) {
+                    //println!("Path from {:?}: {:?}", start, path);
+                    Some((delta + path.len() * 10, *path.first().unwrap_or(start)))
+                } else {
+                    None
+                }
+            })
+            .min_by_key(|(d, _)| *d)
+        {
+            Some(best)
+        } else {
+            None
+        }
+    }
+
+    fn round(&mut self) {
+        self.units.sort_unstable_by_key(|it| it.position);
+
+        for curr in 0..self.units.len() {
+            if let Some(next_target_position) = self.closest_fighting_position(
+                self.units[curr].position,
+                self.units[curr].warrior_type.enemy_type(),
+            ) {
+                if let Some(next_position) =
+                    self.next_position(self.units[curr].position, next_target_position)
+                {
+                    // println!(
+                    //     "{:?} -> {:?} ({:?})",
+                    //     self.units[curr].position, next_target_position, next_position
+                    // );
+                    let curr_pos = self.units[curr].position;
+                    self.tiles[curr_pos.0][curr_pos.1] = Tile::Empty;
+                    self.units[curr].position = next_position;
+                    self.tiles[next_position.0][next_position.1] =
+                        Tile::Unit(self.units[curr].warrior_type);
+                } else {
+                    panic!("We have a reachable target but no path to it!");
+                }
+            }
+        }
+    }
+
+    fn from_input(input: Vec<&str>) -> Self {
+        use self::Tile::*;
+        use self::WarriorType::*;
+        let width = input[0].len();
+        let height = input.len();
+        let mut inner_vec = Vec::new();
+        inner_vec.resize(height, Empty);
+        let mut tiles = Vec::new();
+        tiles.resize(width, inner_vec);
+
+        let mut units = Vec::new();
+        for (y, line) in input.iter().enumerate() {
+            for (x, c) in line.chars().enumerate() {
+                tiles[x][y] = match c {
+                    '.' => Empty,
+                    '#' => Wall,
+                    'E' => {
+                        units.push(Warrior {
+                            warrior_type: Elve,
+                            position: Position(x, y),
+                            health: 300,
+                        });
+                        Unit(Elve)
+                    }
+                    'G' => {
+                        units.push(Warrior {
+                            warrior_type: Goblin,
+                            position: Position(x, y),
+                            health: 300,
+                        });
+                        Unit(Goblin)
+                    }
+                    c => panic!("Unexpected input character '{}'", c),
+                }
+            }
+        }
+
+        Game {
+            units,
+            tiles,
+            width,
+            height,
+        }
+    }
+}
+
+impl Display for Game {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
+        use self::Tile::*;
+        for y in 0..self.height {
+            let mut line = String::with_capacity(self.width);
+            for x in 0..self.width {
+                if let Some(warrior) = self.units.iter().find(|it| it.position == Position(x, y)) {
+                    line.push(match warrior.warrior_type {
+                        WarriorType::Elve => 'E',
+                        WarriorType::Goblin => 'G',
+                    });
+                } else {
+                    line.push(match &self.tiles[x][y] {
+                        Empty => '.',
+                        Wall => '#',
+                        Unit(WarriorType::Elve) => 'E',
+                        Unit(WarriorType::Goblin) => 'G',
+                    });
+                }
+            }
+            f.write_str(&line)?;
+            f.write_str(&"\n")?;
+        }
+        Ok(())
+    }
+}
+
+#[derive(Debug)]
+struct Map {
+    fields: Vec<Vec<MapTile>>,
+    width: usize,
+    height: usize,
+}
+
+#[derive(PartialEq, Debug)]
+enum MapTile {
+    Empty,
+    TargetNonOccupied,
+    Occupied,
+}
+
+impl Display for Map {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
+        use self::MapTile::*;
+        for y in 0..self.height {
+            let mut line = String::with_capacity(self.width);
+            for x in 0..self.width {
+                line.push(match &self.fields[x][y] {
+                    Empty => '.',
+                    Occupied => 'X',
+                    TargetNonOccupied => 'o',
+                });
+            }
+            f.write_str(&line)?;
+            f.write_str(&"\n")?;
+        }
+        Ok(())
+    }
+}
+
+impl Map {
+    fn from_game(game: &Game, clear: Position) -> Self {
+        let mut fields = Vec::with_capacity(game.width);
+        for x in 0..game.width {
+            let mut new = Vec::with_capacity(game.height);
+            for y in 0..game.height {
+                new.push(match &game.tiles[x][y] {
+                    Tile::Empty => MapTile::Empty,
+                    _ => MapTile::Occupied,
+                });
+            }
+            fields.push(new);
+        }
+        fields[clear.0][clear.1] = MapTile::Empty;
+        Map {
+            fields: fields,
+            width: game.width,
+            height: game.height,
+        }
+    }
+
+    fn shortest_path(&self, from: Position, to: Position) -> Option<Vec<Position>> {
+        if to == from {
+            return Some(vec![]);
+        }
+        if self.fields[from.0][from.1] != MapTile::Empty {
+            return None;
+        }
+        let mut open: VecDeque<(Option<Position>, Position)> = VecDeque::new();
+        open.push_back((None, from));
+        let mut predecessors: HashMap<Position, Option<Position>> = HashMap::new();
+
+        while let Some((predecessor, curr_pos)) = open.pop_front() {
+            predecessors.insert(curr_pos, predecessor);
+            if curr_pos == to {
+                break;
+            }
+            for pos in curr_pos.neighbors(self.width, self.height) {
+                if !predecessors.contains_key(&pos) && !open.iter().any(|it| it.1 == pos) {
+                    open.push_back((Some(curr_pos), pos));
+                }
+            }
+        }
+
+        if let Some(Some(_)) = predecessors.get(&to) {
+            let mut result: Vec<Position> = Vec::new();
+            let mut current = to;
+            while let Some(Some(predecessor)) = predecessors.get(&current) {
+                result.push(*predecessor);
+                current = *predecessor;
+            }
+            result.reverse();
+            Some(result)
+        } else {
+            None
+        }
+    }
+
+    fn find_closest_target(&self, from: Position) -> Option<Position> {
+        // println!("{}", self);
+        let mut open: VecDeque<(usize, Position)> = VecDeque::new();
+        open.push_back((0, from));
+        let mut visited: HashSet<Position> = HashSet::new();
+        let mut current_found_distance = usize::max_value();
+        let mut candidates: Vec<Position> = Vec::new();
+
+        while let Some((curr_dist, curr_pos)) = open.pop_front() {
+            if curr_dist > current_found_distance {
+                break;
+            }
+            if self.fields[curr_pos.0][curr_pos.1] == MapTile::TargetNonOccupied {
+                candidates.push(curr_pos);
+                current_found_distance = curr_dist;
+                // all others would have a higher distance and therefore are not relevant
+                continue;
+            }
+            for pos in curr_pos.neighbors(self.width, self.height) {
+                if !visited.contains(&pos) && !open.iter().any(|it| it.1 == pos) {
+                    open.push_back((curr_dist + 1, pos));
+                }
+            }
+            visited.insert(curr_pos);
+        }
+
+        candidates.sort_unstable();
+        if let Some(x) = candidates.first() {
+            Some(*x)
+        } else {
+            None
+        }
+    }
+}

src/tasks/mod.rs

@@ -12,3 +12,4 @@ pub mod day11;
 pub mod day12;
 pub mod day13;
 pub mod day14;
+pub mod day15;