From 080499077affaff005d4404910b64d487e2d685e Mon Sep 17 00:00:00 2001
From: Greg Burri <greg.burri@gmail.com>
Date: Sat, 24 Dec 2022 01:30:57 +0100
Subject: [PATCH] Day 18 part 1

---
 src/day18.rs | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++
 src/days.rs  |   5 +++
 src/main.rs  |   2 +
 3 files changed, 111 insertions(+)
 create mode 100644 src/day18.rs

diff --git a/src/day18.rs b/src/day18.rs
new file mode 100644
index 0000000..a75ddb7
--- /dev/null
+++ b/src/day18.rs
@@ -0,0 +1,104 @@
+pub struct Cube {
+    x: i32,
+    y: i32,
+    z: i32,
+}
+
+pub fn parse(input: &str) -> Vec<Cube> {
+    input
+        .lines()
+        .map(|l| {
+            let xyz: Vec<i32> = l
+                .trim()
+                .split(',')
+                .map(|v| str::parse(v).unwrap())
+                .collect();
+            Cube {
+                x: xyz[0],
+                y: xyz[1],
+                z: xyz[2],
+            }
+        })
+        .collect()
+}
+
+pub fn surface(cubes: &[Cube]) -> i32 {
+    let mut matrix: Vec<Vec<Vec<bool>>> = Vec::new();
+
+    for c in cubes {
+        for _ in matrix.len()..=c.x as usize {
+            matrix.push(Vec::new())
+        }
+        for _ in matrix[c.x as usize].len()..=c.y as usize {
+            matrix[c.x as usize].push(Vec::new())
+        }
+        for _ in matrix[c.x as usize][c.y as usize].len()..=c.z as usize {
+            matrix[c.x as usize][c.y as usize].push(false)
+        }
+        matrix[c.x as usize][c.y as usize][c.z as usize] = true;
+    }
+
+    let mut surface: i32 = 0;
+    for x in 0..matrix.len() as i32 {
+        for y in 0..matrix[x as usize].len() as i32 {
+            for z in 0..matrix[x as usize][y as usize].len() as i32 {
+                if matrix[x as usize][y as usize][z as usize] {
+                    for (dx, dy, dz) in [
+                        (1, 0, 0),
+                        (-1, 0, 0),
+                        (0, 1, 0),
+                        (0, -1, 0),
+                        (0, 0, 1),
+                        (0, 0, -1),
+                    ] {
+                        let (x, y, z) = (x + dx, y + dy, z + dz);
+                        if x < 0
+                            || x >= matrix.len() as i32
+                            || y < 0
+                            || y >= matrix[x as usize].len() as i32
+                            || z < 0
+                            || z >= matrix[x as usize][y as usize].len() as i32
+                            || !matrix[x as usize][y as usize][z as usize]
+                        {
+                            surface = surface + 1;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    surface
+}
+
+pub fn surface_without_trapped_air(cubes: &[Cube]) -> i32 {
+    0 // TODO
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    static CUBES: &str = "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";
+
+    #[test]
+    fn part1() {
+        let cubes = parse(CUBES);
+        assert_eq!(surface(&cubes), 64);
+    }
+
+    #[test]
+    fn part2() {}
+}
diff --git a/src/days.rs b/src/days.rs
index c272123..2dc6343 100644
--- a/src/days.rs
+++ b/src/days.rs
@@ -178,3 +178,8 @@ pub fn day17() -> String {
         day17::height(1_000_000_000_000, &movements)
     )
 }
+
+pub fn day18() -> String {
+    let cubes = day18::parse(&fs::read_to_string("data/day18.input").unwrap());
+    format!("part1: {}, part2: {}", day18::surface(&cubes), 0)
+}
diff --git a/src/main.rs b/src/main.rs
index c030be0..c74cfe5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -20,6 +20,7 @@ mod day14;
 mod day15;
 mod day16;
 mod day17;
+mod day18;
 mod days;
 
 #[derive(Parser, Debug)]
@@ -53,6 +54,7 @@ fn main() {
         days::day15,
         days::day16,
         days::day17,
+        days::day18,
     ];
 
     let args = Args::parse();
-- 
2.45.2