[CLEANUP] Cleaned up day 16

.run/run-day-16.run.xml

@@ -0,0 +1,19 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="run-day-16" type="CargoCommandRunConfiguration" factoryName="Cargo Command">
+    <option name="command" value="run --package advent-of-code-2022-rust --bin advent-of-code-2022-rust --release -- -d 16" />
+    <option name="workingDirectory" value="file://$PROJECT_DIR$" />
+    <option name="channel" value="DEFAULT" />
+    <option name="requiredFeatures" value="true" />
+    <option name="allFeatures" value="false" />
+    <option name="emulateTerminal" value="false" />
+    <option name="withSudo" value="false" />
+    <option name="buildTarget" value="REMOTE" />
+    <option name="backtrace" value="SHORT" />
+    <envs />
+    <option name="isRedirectInput" value="false" />
+    <option name="redirectInputPath" value="" />
+    <method v="2">
+      <option name="CARGO.BUILD_TASK_PROVIDER" enabled="true" />
+    </method>
+  </configuration>
+</component>

input/day17_example.txt

@@ -0,0 +1 @@
+>>><<><>><<<>><>>><<<>>><<<><<<>><>><<>>

input/day18_example.txt

@@ -0,0 +1,13 @@
+2,2,2
+1,2,2
+3,2,2
+2,1,2
+2,3,2
+2,2,1
+2,2,3
+2,2,4
+2,2,6
+1,2,5
+3,2,5
+2,1,5
+2,3,5

src/day16.rs

@@ -1,3 +1,5 @@
+use std::collections::HashMap;
+use crate::day16::ValveStep::{MoveTo, OpenValve};
 use crate::day_solver::DaySolver;
 
 use super::util;
@@ -5,65 +7,204 @@ use super::util;
 pub struct Day16 {
     valves: Vec<Valve>,
     initial_valve_idx: usize,
+    // valve_names: Vec<String>
 }
 
 impl Day16 {
 
     pub fn create() -> Self {
-        let lines = util::read_file("input/day16_example.txt");
-        // let lines = util::read_file("input/day16.txt");
+        // let lines = util::read_file("input/day16_example.txt");
+        let lines = util::read_file("input/day16.txt");
 
         // We first map all the valve names to indexes for performance reasons:
         let valve_names = lines.iter()
-            .map(|s| s.split_whitespace().skip(1).next().unwrap().to_string())
+            .map(|s| s.split_whitespace().nth(1).unwrap().to_string())
             .collect::<Vec<String>>();
 
         // Put the input into the day struct
         return Day16 {
-            valves: lines.iter().enumerate().map(|(i, s)| {
-                let mut s_split = s.split(";");
-                let flow_rate = s_split.next().unwrap().split("rate=").skip(1).next().unwrap().parse::<u32>().unwrap();
-                let connections = (&s_split.next().unwrap()["tunnels lead to valves ".len()..].trim()).split(", ")
+            valves: lines.iter().enumerate().map(|(_, s)| {
+                let mut s_split = s.split(';');
+                let flow_rate = s_split.next().unwrap().split("rate=").nth(1).unwrap().parse::<u32>().unwrap();
+                let connections = s_split.next().unwrap()["tunnels lead to valves ".len()..].trim().split(", ")
                     .map(|n| valve_names.iter().position(|nn| n.eq(nn)).unwrap())
                     .collect();
                 Valve {
-                    id: i, flow_rate, connections
+                    // id: i,
+                    flow_rate, connections
                 }
             }).collect(),
-            initial_valve_idx: valve_names.iter().position(|n| n == "AA").unwrap()
+            initial_valve_idx: valve_names.iter().position(|n| n == "AA").unwrap(),
+            // valve_names
         }
     }
 
-    fn is_open(valve_idx: &usize, open_valves_mask: &u64) -> bool {
-        open_valves_mask & (1u64 << valve_idx) != 0
-    }
-
-    fn is_closed(valve_idx: &usize, open_valves_mask: &u64) -> bool {
-        !Self::is_open(valve_idx, open_valves_mask)
-    }
-
     fn set_open(valve_idx: &usize, cur_open_valves_mask: &u64) -> u64 {
         cur_open_valves_mask.clone() | (1u64 << valve_idx)
     }
 
-    fn find_best_option(&self, cur_valve_idx: &usize, open_valves_mask: u64, cur_flow_rate: u32, minutes_left: u32) -> u32 {
+    fn is_open(valve_idx: &usize, open_valves_mask: &u64) -> bool {
+        open_valves_mask & (1u64 << valve_idx) != 0
+    }
 
-        if minutes_left == 0 { return 0; }
+    // fn is_closed(valve_idx: &usize, open_valves_mask: &u64) -> bool {
+    //     !Self::is_open(valve_idx, open_valves_mask)
+    // }
+    //
+    // fn calc_flow_rate(&self, open_valves_mask: &u64) -> u32 {
+    //     let mut res = 0;
+    //     for i in 0..self.valves.len() {
+    //         if Self::is_open(&i, open_valves_mask) {
+    //             res += self.valves[i].flow_rate
+    //         }
+    //     }
+    //     res
+    // }
 
-        let cur_valve = &self.valves.get(*cur_valve_idx).unwrap();
-        let mut next_step_options = Vec::new();
-        if Self::is_closed(&cur_valve_idx, &open_valves_mask) && cur_valve.flow_rate > 0 {
+    fn should_valve_be_opened(&self, valve_idx: &usize, open_valves_mask: &u64) -> bool {
+        if Self::is_open(valve_idx, open_valves_mask) { false }
+        else if let Some(valve) = self.valves.get(*valve_idx) {
+            valve.flow_rate > 0
+        } else { false }
+    }
+
+    fn find_best_option_pt2(&self, valve_state: ValveStatePt2, cur_flow_rate: u32, cache: &mut HashMap<ValveStatePt2, BestOptionPt2>) -> BestOptionPt2 {
+
+        if valve_state.minutes_left == 0 {
+            return BestOptionPt2 {
+                // my_step: ValveStep::None,
+                // elephant_step: ValveStep::None,
+                total_flow: 0,
+                // cur_flow: cur_flow_rate
+            }
+        }
+
+        if let Some(res) = cache.get(&valve_state) {
+            return res.to_owned();
+        }
+
+        let mut my_options = Vec::new();
+        let mut elephant_options = Vec::new();
+
+        if self.should_valve_be_opened(&valve_state.my_position, &valve_state.open_valves_mask) {
             // One option is to open the valve at the current position
-            next_step_options.push(
-                self.find_best_option(cur_valve_idx, Self::set_open(&cur_valve_idx, &open_valves_mask), cur_flow_rate + cur_valve.flow_rate, minutes_left - 1)
-            );
-        } else {
+            my_options.push(OpenValve(valve_state.my_position));
+        }
+
+        if valve_state.my_position != valve_state.elephant_position && self.should_valve_be_opened(&valve_state.elephant_position, &valve_state.open_valves_mask) {
+            elephant_options.push(OpenValve(valve_state.elephant_position));
+        }
+
         // We try and move to an adjacent valve, see if we can be more useful there
-            for connection in &cur_valve.connections {
-                next_step_options.push(self.find_best_option(connection, open_valves_mask, cur_flow_rate, minutes_left - 1));
+        let my_valve = &self.valves[valve_state.my_position];
+        for connection in my_valve.connections.iter() {
+            my_options.push(MoveTo(connection.to_owned()))
+        }
+
+        let elephant_valve = &self.valves[valve_state.elephant_position];
+        for connection in elephant_valve.connections.iter() {
+            elephant_options.push(MoveTo(connection.to_owned()))
+        }
+
+        // Now we try all combinations of my and elephants options:
+        let mut best: u32 = 0;
+        // let mut my_best_step = None;
+        // let mut elephant_best_step = None;
+        let next_minutes_left = valve_state.minutes_left - 1;
+        for my_option in my_options {
+
+            let mut my_next_position = valve_state.my_position;
+            let mut next_valve_mask_for_me = valve_state.open_valves_mask;
+            let mut next_flow_rate_for_me = cur_flow_rate;
+
+            match my_option {
+                MoveTo(idx) => my_next_position = idx,
+                OpenValve(idx) => {
+                    next_valve_mask_for_me = Self::set_open(&idx, &next_valve_mask_for_me);
+                    next_flow_rate_for_me += self.valves[idx].flow_rate
                 }
             }
-        return cur_flow_rate + next_step_options.iter().max().unwrap();
+            for elephant_option in &elephant_options {
+
+                let mut next_valve_mask = next_valve_mask_for_me;
+                let mut next_flow_rate = next_flow_rate_for_me;
+                let mut elephant_next_position = valve_state.elephant_position;
+
+                match elephant_option {
+                    MoveTo(idx) => elephant_next_position = *idx,
+                    OpenValve(idx) => {
+                        next_valve_mask = Self::set_open(idx, &next_valve_mask);
+                        next_flow_rate += self.valves[*idx].flow_rate
+                    }
+                }
+
+                let res = self.find_best_option_pt2(ValveStatePt2::new(my_next_position, elephant_next_position, next_valve_mask, next_minutes_left), next_flow_rate, cache);
+                if best == 0 || res.total_flow > best {
+                    best = res.total_flow;
+                    // my_best_step = Some(my_option);
+                    // elephant_best_step = Some(elephant_option.to_owned());
+                }
+            }
+        }
+
+        let res = BestOptionPt2 {
+            // my_step: my_best_step.unwrap(),
+            // elephant_step: elephant_best_step.unwrap(),
+            // cur_flow: cur_flow_rate,
+            total_flow: best + cur_flow_rate
+        };
+        cache.insert(valve_state, res.to_owned());
+        res
+    }
+
+    fn find_best_option(&self, valve_state: ValveState, cur_flow_rate: u32, cache: &mut HashMap<ValveState, BestOptionResult>) -> Option<BestOptionResult> {
+
+        if valve_state.minutes_left == 0 { return None }
+
+        if let Some(res) = cache.get(&valve_state) {
+            return Some(res.clone());
+        }
+
+        let cur_valve = &self.valves.get(valve_state.my_position).unwrap();
+        let mut best_step_option: Option<ValveStep> = None;
+        let mut best_step_result_option: Option<BestOptionResult> = None;
+        if self.should_valve_be_opened(&valve_state.my_position, &valve_state.open_valves_mask) {
+            // One option is to open the valve at the current position
+            let new_open_valves_mask = Self::set_open(&valve_state.my_position, &valve_state.open_valves_mask);
+            best_step_result_option = self.find_best_option(ValveState::new(valve_state.my_position, new_open_valves_mask, valve_state.minutes_left - 1), cur_flow_rate + cur_valve.flow_rate, cache);
+            best_step_option = Some(OpenValve(valve_state.my_position));
+        }
+        // We try and move to an adjacent valve, see if we can be more useful there
+        for connection in cur_valve.connections.iter().rev() {
+            let next_step_result = self.find_best_option(ValveState::new(connection.to_owned(), valve_state.open_valves_mask, valve_state.minutes_left - 1), cur_flow_rate, cache);
+            if best_step_result_option.is_none() || next_step_result.as_ref().unwrap().total_flow > best_step_result_option.as_ref().unwrap().total_flow {
+                best_step_result_option = next_step_result;
+                best_step_option = Some(MoveTo(connection.to_owned()));
+            }
+        }
+
+        let Some(best_step) = best_step_option else { panic!("Couldn't find a good step?") };
+
+        let mut flow_per_step = Vec::with_capacity(valve_state.minutes_left as usize);
+        flow_per_step.push(cur_flow_rate);
+
+        let mut steps = Vec::with_capacity(valve_state.minutes_left as usize);
+        steps.push(best_step);
+
+        let mut best_next_flow = 0;
+        if let Some(best_step_result) = best_step_result_option {
+            flow_per_step.extend(best_step_result.flow_per_step.iter());
+            steps.extend(best_step_result.steps.iter());
+            best_next_flow = best_step_result.total_flow;
+        }
+
+        let step_result = BestOptionResult {
+            total_flow: best_next_flow + cur_flow_rate,
+            flow_per_step,
+            steps,
+        };
+        cache.insert(valve_state, step_result.clone());
+        Some(step_result)
     }
 }
 
@@ -71,17 +212,90 @@ impl DaySolver for Day16 {
 
 
     fn solve_part1(&mut self) -> String {
-        self.find_best_option(&self.initial_valve_idx, 0, 0, 10).to_string()
+        let mut cache= HashMap::new();
+        // let example_flows = [0, 0, 0, 20, 20, 20, 33, 33, 33, 33, 54, 54, 54, 54, 54, 54, 54, 54, 76, 76, 76, 76, 79, 79, 79, 81, 81, 81, 81, 81, 81];
+        // let mut prev_best: u32 = 0;
+        // let mut example_running_total = 0;
+        // for i in 1..31u32 {
+        //     let Some(best) = self.find_best_option(ValveState::new(self.initial_valve_idx, 0, i), 0, &mut cache) else { panic!("Not best!")};
+        //     let cur_example_flow = example_flows[i as usize];
+        //     example_running_total += cur_example_flow;
+        //     println!("Best in {} minutes is {}, so I guess the flow is {}, while example flow is {} (example running total {})", i, best.total_flow, best.total_flow - prev_best, cur_example_flow, example_running_total);
+        //     prev_best = best.total_flow;
+        // }
+
+        let best = self.find_best_option(ValveState::new(self.initial_valve_idx, 0, 30), 0, &mut cache).unwrap();
+        // for i in 0..best.steps.len() {
+        //     println!("Step {}", i + 1);
+        //     match best.steps[i] {
+        //         ValveStep::OpenValve(v) => println!("Opening valve {}", self.valve_names[v]),
+        //         ValveStep::MoveTo(v ) => println!("Moving to valve {}", self.valve_names[v])
+        //     }
+        //     println!("The flow is now {}\n", best.flow_per_step[i]);
+        // }
+        best.total_flow.to_string()
     }
 
     fn solve_part2(&mut self) -> String {
-        return 0.to_string();
+
+        let mut cache= HashMap::new();
+        let best = self.find_best_option_pt2(ValveStatePt2::new(self.initial_valve_idx, self.initial_valve_idx, 0, 26), 0, &mut cache);
+
+        best.total_flow.to_string()
     }
 }
 
 #[derive(Debug, Clone)]
 struct Valve {
-    id: usize,
+    // id: usize,
     flow_rate: u32,
     connections: Vec<usize>
 }
+
+#[derive(Debug, Clone, Hash, Eq, PartialEq)]
+struct ValveState {
+    my_position: usize,
+    open_valves_mask: u64,
+    minutes_left: u32
+}
+
+impl ValveState {
+    fn new(cur_valve_idx: usize, open_valves_mask: u64, minutes_left: u32) -> Self{
+        ValveState { my_position: cur_valve_idx, open_valves_mask, minutes_left }
+    }
+}
+
+#[derive(Debug, Clone, Hash, Eq, PartialEq)]
+struct ValveStatePt2 {
+    my_position: usize,
+    elephant_position: usize,
+    open_valves_mask: u64,
+    minutes_left: u32
+}
+
+#[derive(Debug, Clone, Copy)]
+struct BestOptionPt2 {
+    // my_step: ValveStep,
+    // elephant_step: ValveStep,
+    total_flow: u32,
+    // cur_flow: u32
+}
+
+impl ValveStatePt2 {
+    fn new(my_position: usize, elephant_position: usize, open_valves_mask: u64, minutes_left: u32) -> Self{
+        ValveStatePt2 { my_position, elephant_position, open_valves_mask, minutes_left }
+    }
+}
+
+#[derive(Debug, Clone)]
+struct BestOptionResult {
+    steps: Vec<ValveStep>,
+    flow_per_step: Vec<u32>,
+    total_flow: u32
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+enum ValveStep {
+    OpenValve(usize),
+    MoveTo(usize),
+}

src/day17.rs

@@ -0,0 +1,148 @@
+use std::fmt::{Display, Formatter};
+use lazy_static::lazy_static;
+use crate::day_solver::DaySolver;
+use crate::util::{Coord, Grid};
+
+use super::util;
+
+pub struct Day17 {
+    jet_pattern: Vec<char>
+}
+
+impl Day17 {
+
+    pub fn create() -> Self {
+        // let lines = util::read_file("input/day17_example.txt");
+        let lines = util::read_file("input/day17.txt");
+
+        // Put the input into the day struct
+        return Day17 {
+            jet_pattern: lines.first().unwrap().chars().collect()
+        }
+    }
+
+    fn rock_can_occupy_pos(&self, rock: &Grid<bool>, pos: &Coord<usize>, grid: &Grid<CaveCell>) -> bool {
+
+        if rock.width + pos.x > grid.width {
+            return false;
+        }
+
+        for y in 0..rock.height() {
+            for x in 0..rock.width {
+                if rock.get(&x, &y) == &true && grid.get(&(x + pos.x), &(pos.y + y)) == &CaveCell::Rock {
+                    return false
+                }
+            }
+        }
+        return true;
+    }
+}
+
+impl DaySolver for Day17 {
+
+
+    fn solve_part1(&mut self) -> String {
+
+        let mut cave = Grid {
+            data: vec![CaveCell::Empty; 7 * 2022 * 4],
+            width: 7
+        };
+
+        let mut cur_spawn_height = 3;
+        let mut jet_iter = self.jet_pattern.iter().cycle();
+        for i in 0..2022 {
+            // Spawn the rock
+            let Some(rock) = ROCK_SHAPES.get(i % ROCK_SHAPES.len()) else { panic!("Can't find rock {}", i % ROCK_SHAPES.len())};
+            // The rock_pos is the bottom-left corner of the rock
+            let mut rock_pos = Coord::new(2, cur_spawn_height);
+            loop {
+                match jet_iter.next() {
+                    Some('>') => {
+                        let next_pos = Coord::new(rock_pos.x + 1, rock_pos.y);
+                        if self.rock_can_occupy_pos(rock, &next_pos, &cave) {
+                            rock_pos = next_pos;
+                        }
+                    }
+                    Some('<') => {
+                        if rock_pos.x > 0 {
+                            let next_pos = Coord::new(rock_pos.x - 1, rock_pos.y);
+                            if self.rock_can_occupy_pos(rock, &next_pos, &cave) {
+                                rock_pos = next_pos;
+                            }
+                        }
+                    }
+                    m => { panic!("Unknown rock movement: {}...", m.unwrap_or(&'?')); }
+                }
+
+                // Now we move the rock down
+                if rock_pos.y == 0 {
+                    break;
+                }
+                let next_pos = Coord::new(rock_pos.x, rock_pos.y - 1);
+                if self.rock_can_occupy_pos(rock, &next_pos, &cave) {
+                    rock_pos = next_pos;
+                } else {
+                    break;
+                }
+            }
+            // place the rock
+            for y in 0..rock.height() {
+                for x in 0..rock.width {
+                    if rock.get(&x, &y) == &true {
+                        cave.set(&(rock_pos.x + x), &(rock_pos.y + y), CaveCell::Rock);
+                    }
+                }
+            }
+
+            cur_spawn_height = cur_spawn_height.max(rock_pos.y + rock.height() + 3);
+
+        }
+        cave.print_range(0, 7, 0, 40);
+        return (cur_spawn_height-3).to_string();
+    }
+
+    fn solve_part2(&mut self) -> String {
+        return 0.to_string();
+    }
+}
+
+lazy_static! {
+    static ref ROCK_SHAPES: Vec<Grid<bool>> = vec![
+        Grid { data: vec![
+            true, true, true, true],
+            width: 4},
+        Grid { data: vec![
+            false, true, false,
+            true, true, true,
+            false, true, false],
+            width: 3},
+        Grid {data: vec![
+            true, true, true,
+            false, false, true,
+            false, false, true,
+        ], width: 3},
+        Grid { data: vec![
+            true,
+            true,
+            true,
+            true], width: 1},
+        Grid { data: vec![
+            true, true,
+            true, true],
+            width: 2  },
+    ];
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+enum CaveCell {
+    Rock, Empty
+}
+
+impl Display for CaveCell {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            CaveCell::Rock => write!(f, "#"),
+            CaveCell::Empty => write!(f, ".")
+        }
+    }
+}

src/day18.rs

@@ -0,0 +1,205 @@
+use std::collections::{HashSet};
+use crate::day18::VoxelState::{Air, Unknown};
+
+use crate::day_solver::DaySolver;
+
+use super::util;
+
+
+pub struct Day18 {
+    voxels: HashSet<Vec3>
+}
+
+impl Day18 {
+
+    pub fn create() -> Self {
+        // let lines = util::read_file("input/day18_example.txt");
+        let lines = util::read_file("input/day18.txt");
+
+        let voxels = lines.iter().map(|l| {
+            let mut c_iter = l.split(",").map(|c| c.parse().unwrap());
+            Vec3 {
+                x: c_iter.next().unwrap(),
+                y: c_iter.next().unwrap(),
+                z: c_iter.next().unwrap()
+            }
+        }).collect::<HashSet<Vec3>>();
+
+        // Put the input into the day struct
+        return Day18 { voxels }
+    }
+}
+
+impl DaySolver for Day18 {
+
+
+    fn solve_part1(&mut self) -> String {
+        
+        let mut sides = 0;
+        for voxel in &self.voxels {
+            // We just scan all sides if there are voxels there
+            if !self.voxels.contains(&voxel.moved(-1, 0, 0)) { sides += 1 };
+            if !self.voxels.contains(&voxel.moved(1, 0, 0)) { sides += 1 };
+            if !self.voxels.contains(&voxel.moved(0, -1, 0)) { sides += 1 };
+            if !self.voxels.contains(&voxel.moved(0, 1, 0)) { sides += 1 };
+            if !self.voxels.contains(&voxel.moved(0, 0, -1)) { sides += 1 };
+            if !self.voxels.contains(&voxel.moved(0, 0, 1)) { sides += 1 };
+        }
+        return sides.to_string();
+    }
+
+    fn solve_part2(&mut self) -> String {
+
+        // We need to find the cubes that can't be reached 
+        let x_min = self.voxels.iter().map(|v| v.x).min().unwrap();
+        let x_max = self.voxels.iter().map(|v| v.x).max().unwrap();
+        let y_min = self.voxels.iter().map(|v| v.y).min().unwrap();
+        let y_max = self.voxels.iter().map(|v| v.y).max().unwrap();
+        let z_min = self.voxels.iter().map(|v| v.z).min().unwrap();
+        let z_max = self.voxels.iter().map(|v| v.z).max().unwrap();
+
+        let width = (x_max + 1 - x_min) as usize;
+        let height = (y_max + 1 - y_min) as usize;
+        let depth = (z_max + 1 - z_min) as usize;
+
+
+        let mut grid = Grid3D {
+            data: vec![Unknown; width * depth * height],
+            width,
+            height,
+            depth,
+            offset: Vec3 { x: x_min, y: y_min, z: z_min },
+            max: Vec3{ x: x_max, y: y_max, z: z_max}
+        };
+
+        for vox in &self.voxels {
+            grid.set(&vox.x, &vox.y, &vox.z, VoxelState::Rock);
+        }
+
+        let mut queue = Vec::new();
+        // Now we mark all voxels on the edge as air (if they're not rock)
+        for x in grid.offset.x..grid.max.x+1 {
+            for y in grid.offset.y..grid.max.y+1 {
+                queue_if_unknown(&mut grid, &mut queue, &x, &y, &z_min);
+                queue_if_unknown(&mut grid, &mut queue, &x, &y, &z_max);
+            }
+            for z in grid.offset.z..grid.max.z+1 {
+                queue_if_unknown(&mut grid, &mut queue, &x, &y_min, &z);
+                queue_if_unknown(&mut grid, &mut queue, &x, &y_max, &z);
+            }
+        }
+        for z in z_min..z_max + 1 {
+            for y in y_min..y_max + 1 {
+                queue_if_unknown(&mut grid, &mut queue, &x_min, &y, &z);
+                queue_if_unknown(&mut grid, &mut queue, &x_max, &y, &z);
+            }
+        }
+
+        // We search one extra cube around the actual grid, so that the search doesn't get blocked
+        // by rocks hitting the outer edge:
+        queue.push(grid.offset.moved(-1, 0, 0));
+        while let Some(pos) = queue.pop() {
+            // If we got here, it means that "pos" is in air, and we need to check if the neighbors are as well
+            try_pos(&mut grid, &mut queue, &pos, 1, 0, 0);
+            try_pos(&mut grid, &mut queue, &pos, -1, 0, 0);
+            try_pos(&mut grid, &mut queue, &pos, 0, 1, 0);
+            try_pos(&mut grid, &mut queue, &pos, 0, -1, 0);
+            try_pos(&mut grid, &mut queue, &pos, 0, 0, 1);
+            try_pos(&mut grid, &mut queue, &pos, 0, 0, -1);
+        }
+
+        // and finally, we do the same check (basically) as in pt 1:
+        let mut sides = 0;
+        for voxel in &self.voxels {
+            // We just scan all sides if there are voxels there
+            if grid.get(&(voxel.x + 1), &voxel.y, &voxel.z) == &Air { sides += 1 };
+            if grid.get(&(voxel.x - 1), &voxel.y, &voxel.z) == &Air { sides += 1 };
+            if grid.get(&voxel.x, &(voxel.y + 1), &voxel.z) == &Air { sides += 1 };
+            if grid.get(&voxel.x, &(voxel.y - 1), &voxel.z) == &Air { sides += 1 };
+            if grid.get(&voxel.x, &voxel.y, &(voxel.z + 1)) == &Air { sides += 1 };
+            if grid.get(&voxel.x, &voxel.y, &(voxel.z - 1)) == &Air { sides += 1 };
+        }
+        // println!("{:?}", grid.data);
+        // return grid.data.iter().filter(|v| v == &&Unknown).count().to_string();
+        sides.to_string()
+    }
+
+}
+
+fn try_pos(grid: &mut Grid3D, queue: &mut Vec<Vec3>, pos: &Vec3, offset_x: i32, offset_y: i32, offset_z: i32) {
+    let x = pos.x + offset_x;
+    let y =  pos.y + offset_y;
+    let z = pos.z + offset_z;
+    queue_if_unknown(grid, queue, &x, &y, &z);
+}
+
+fn queue_if_unknown(grid: &mut Grid3D, queue: &mut Vec<Vec3>, x: &i32, y: &i32, z: &i32) {
+    if grid.get(x, y, z) == &Unknown {
+        grid.set(x, y, z, Air);
+        queue.push(Vec3::new(*x, *y, *z))
+    }
+}
+
+
+#[derive(Debug, PartialEq, Eq, Hash, Clone)]
+struct Vec3 {
+    x: i32,
+    y: i32,
+    z: i32
+}
+
+impl Vec3 {
+    fn moved(&self, x: i32, y: i32, z: i32) -> Vec3 {
+        Vec3 {
+            x: self.x + x,
+            y: self.y + y,
+            z: self.z + z
+        }
+    }
+
+    fn new(x: i32, y: i32, z: i32) -> Vec3 {
+        return Vec3 {
+            x, y, z
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+struct Grid3D {
+    data: Vec<VoxelState>,
+    width: usize,
+    height: usize,
+    depth: usize,
+    offset: Vec3,
+    max: Vec3
+}
+
+impl Grid3D {
+    fn set(&mut self, x: &i32, y: &i32, z: &i32, value: VoxelState) {
+
+        if x < &self.offset.x || y < &self.offset.y || z < &self.offset.z {
+            panic!("Invalid position to update the grid: ({}, {}, {})", x, y, z);
+        }
+
+        let coord = self.grid_coord(&x, &y, &z);
+        self.data[coord] = value;
+    }
+
+    fn get(&self, x: &i32, y: &i32, z: &i32) -> &VoxelState {
+        if x < &self.offset.x || y < &self.offset.y || z < &self.offset.z || 
+            x > &self.max.x || y > &self.max.y || z > &self.max.z {
+                &VoxelState::Air
+            } else {
+                &self.data[self.grid_coord(x, y, z)]
+            }
+    }
+
+    fn grid_coord(&self, x: &i32, y: &i32, z: &i32) -> usize {
+        (x - self.offset.x) as usize + ((y - self.offset.y) as usize * self.width) + ((z - self.offset.z) as usize * self.width * self.height)
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+enum VoxelState {
+    Air, Rock, Unknown
+}

src/main.rs

@@ -1,3 +1,5 @@
+extern crate core;
+
 use std::time::Instant;
 use crate::day1::Day1;
 use crate::day2::Day2;
@@ -15,6 +17,8 @@ use crate::day13::Day13;
 use crate::day14::Day14;
 use crate::day15::Day15;
 use crate::day16::Day16;
+use crate::day17::Day17;
+use crate::day18::Day18;
 use crate::day_solver::DaySolver;
 
 mod util;
@@ -35,8 +39,10 @@ mod day13;
 mod day14;
 mod day15;
 mod day16;
+mod day17;
+mod day18;
 
-const MAX_DAY: u8 = 15;
+const MAX_DAY: u8 = 17;
 const DEFAULT_BENCHMARK_AMOUNT: u32 = 100;
 
 fn main() {
@@ -116,6 +122,8 @@ fn build_day_solver(day: u8) -> Option<Box<dyn DaySolver>> {
         14 => Some(Box::new(Day14::create())),
         15 => Some(Box::new(Day15::create())),
         16 => Some(Box::new(Day16::create())),
+        17 => Some(Box::new(Day17::create())),
+        18 => Some(Box::new(Day18::create())),
         _ => None
     }
 }

src/util.rs

@@ -84,6 +84,12 @@ pub struct Coord<T> where T: Sized {
     pub y: T
 }
 
+impl<T> Coord<T> where T: Sized {
+    pub(crate) fn new(x: T, y: T) -> Self {
+        Coord { x, y }
+    }
+}
+
 impl <T> Coord<T> where T: Integer + Copy {
     pub fn manhattan_dist(&self, other: &Coord<T>) -> T {
         self.x.max(other.x).sub(self.x.min(other.x)) + self.y.max(other.y).sub(self.y.min(other.y))