feat: day 18

Cargo.lock

@@ -35,6 +35,7 @@ dependencies = [
  "lru-cache",
  "peg",
  "petgraph",
+ "rayon",
  "regex",
  "time",
  "ureq",
@@ -135,6 +136,55 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "crossbeam-channel"
+version = "0.5.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c2dd04ddaf88237dc3b8d8f9a3c1004b506b54b3313403944054d23c0870c521"
+dependencies = [
+ "cfg-if",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "715e8152b692bba2d374b53d4875445368fdf21a94751410af607a5ac677d1fc"
+dependencies = [
+ "cfg-if",
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "01a9af1f4c2ef74bb8aa1f7e19706bc72d03598c8a570bb5de72243c7a9d9d5a"
+dependencies = [
+ "autocfg",
+ "cfg-if",
+ "crossbeam-utils",
+ "memoffset",
+ "scopeguard",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4fb766fa798726286dbbb842f174001dab8abc7b627a1dd86e0b7222a95d929f"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "either"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "90e5c1c8368803113bf0c9584fc495a58b86dc8a29edbf8fe877d21d9507e797"
+
 [[package]]
 name = "eyre"
 version = "0.6.8"
@@ -182,6 +232,15 @@ version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
 
+[[package]]
+name = "hermit-abi"
+version = "0.1.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "62b467343b94ba476dcb2500d242dadbb39557df889310ac77c5d99100aaac33"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "idna"
 version = "0.3.0"
@@ -259,6 +318,15 @@ version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
 
+[[package]]
+name = "memoffset"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5de893c32cde5f383baa4c04c5d6dbdd735cfd4a794b0debdb2bb1b421da5ff4"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "miniz_oxide"
 version = "0.5.4"
@@ -277,6 +345,16 @@ dependencies = [
  "adler",
 ]
 
+[[package]]
+name = "num_cpus"
+version = "1.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f6058e64324c71e02bc2b150e4f3bc8286db6c83092132ffa3f6b1eab0f9def5"
+dependencies = [
+ "hermit-abi",
+ "libc",
+]
+
 [[package]]
 name = "object"
 version = "0.29.0"
@@ -365,6 +443,28 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "rayon"
+version = "1.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6db3a213adf02b3bcfd2d3846bb41cb22857d131789e01df434fb7e7bc0759b7"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cac410af5d00ab6884528b4ab69d1e8e146e8d471201800fa1b4524126de6ad3"
+dependencies = [
+ "crossbeam-channel",
+ "crossbeam-deque",
+ "crossbeam-utils",
+ "num_cpus",
+]
+
 [[package]]
 name = "regex"
 version = "1.7.0"
@@ -415,6 +515,12 @@ dependencies = [
  "webpki",
 ]
 
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
 [[package]]
 name = "sct"
 version = "0.7.0"

Cargo.toml

@@ -20,3 +20,4 @@ regex = "1.7.0"
 petgraph = "0.6.2"
 peg = "0.8.1"
 lru-cache = "0.1.2"
+rayon = "1.6.1"

src/bin/day_18.rs

@@ -0,0 +1,129 @@
+use std::{collections::{HashSet, HashMap}, ops::RangeInclusive};
+
+use aoc_2022::prelude::*;
+use rayon::prelude::*;
+
+type Coord = (isize, isize, isize);
+
+type Input = Vec<Coord>;
+
+fn parse(s: &str) -> Result<Input> {
+    let mut coords = vec![];
+    for line in s.lines() {
+        let coord = ints(line);
+        let coord = (coord[0], coord[1], coord[2]);
+        coords.push(coord);
+    }
+    Ok(coords)
+}
+
+#[derive(Clone, Copy, Eq, Hash, PartialEq)]
+enum Face {
+    X,
+    Y,
+    Z,
+}
+
+#[aoc(day = 18, parse = parse, test_cases = ["day_18.txt"])]
+fn day_18(input: Input) -> Result<()> {
+    // Part 1
+    let mut faces = HashSet::<(Face, Coord)>::new();
+    for cube in &input {
+        let cube_faces = [
+            (Face::X, *cube),
+            (Face::X, (cube.0 + 1, cube.1, cube.2)),
+            (Face::Y, *cube),
+            (Face::Y, (cube.0, cube.1 + 1, cube.2)),
+            (Face::Z, *cube),
+            (Face::Z, (cube.0, cube.1, cube.2 + 1)),
+        ];
+        for face in cube_faces {
+            if faces.contains(&face) {
+                faces.remove(&face);
+            } else {
+                faces.insert(face);
+            }
+        }
+    }
+    println!("Part one: {}", faces.len());
+
+    // Part 2
+    let (x_range, y_range, z_range) = {
+        let min_x = input.iter().map(|c| c.0).min().unwrap();
+        let min_y = input.iter().map(|c| c.1).min().unwrap();
+        let min_z = input.iter().map(|c| c.2).min().unwrap();
+        let max_x = input.iter().map(|c| c.0).max().unwrap();
+        let max_y = input.iter().map(|c| c.1).max().unwrap();
+        let max_z = input.iter().map(|c| c.2).max().unwrap();
+        (min_x..=max_x, min_y..=max_y, min_z..=max_z)
+    };
+
+    let corrected_sa = faces.par_iter().filter(|(face, coord)| {
+        let other = match face {
+            Face::X => (coord.0 - 1, coord.1, coord.2),
+            Face::Y => (coord.0, coord.1 - 1, coord.2),
+            Face::Z => (coord.0, coord.1, coord.2 - 1),
+        };
+        let mut cache = HashMap::new();
+        can_reach_outside(&input, (&x_range, &y_range, &z_range), *coord, &HashSet::new(), &mut cache)
+        || can_reach_outside(&input, (&x_range, &y_range, &z_range), other, &HashSet::new(), &mut cache)
+    }).count();
+
+    println!("Part 2: {corrected_sa}");
+
+    Ok(())
+}
+
+fn can_reach_outside(
+    input: &Input,
+    (x_range, y_range, z_range): (
+        &RangeInclusive<isize>,
+        &RangeInclusive<isize>,
+        &RangeInclusive<isize>,
+    ),
+    position: Coord,
+    visited: &HashSet<Coord>,
+    cache: &mut HashMap<Coord, bool>,
+) -> bool {
+    if let Some(result) = cache.get(&position) {
+        *result
+    } else {
+        let result = if x_range.contains(&position.0) && y_range.contains(&position.1) && z_range.contains(&position.2) {
+            if input.contains(&position) {
+                false
+            } else {
+                let mut visited = visited.clone();
+                visited.insert(position);
+
+                const DIRECTIONS: &[(isize, isize, isize)] = &[
+                    ( 1,  0,  0),
+                    (-1,  0,  0),
+                    ( 0,  1,  0),
+                    ( 0, -1,  0),
+                    ( 0,  0,  1),
+                    ( 0,  0, -1),
+                ];
+
+                let mut can_reach = false;
+
+                for direction in DIRECTIONS {
+                    let new_position = (position.0 + direction.0, position.1 + direction.1, position.2 + direction.2);
+                    if visited.contains(&new_position) {
+                        continue;
+                    }
+                    if can_reach_outside(input, (x_range, y_range, z_range), new_position, &visited, cache) {
+                        can_reach = true;
+                        break;
+                    }
+                }
+
+                can_reach
+            }
+        } else {
+            true
+        };
+
+        cache.insert(position, result);
+        result
+    }
+}

test_cases/day_18.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