Work on day 22 part 1

data/examples/22.txt

@@ -0,0 +1,7 @@
+1,0,1~1,2,1
+0,0,2~2,0,2
+0,2,3~2,2,3
+0,0,4~0,2,4
+2,0,5~2,2,5
+0,1,6~2,1,6
+1,1,8~1,1,9

src/bin/22.rs

@@ -0,0 +1,83 @@
+use std::cmp::max;
+use itertools::Itertools;
+
+advent_of_code::solution!(22);
+
+type XY = (usize, usize);
+type XYZ = (usize, usize, usize);
+
+struct Brick {
+    start: XYZ,
+    end: XYZ,
+}
+
+fn parse(input: &str) -> Vec<Brick> {
+    let mut bricks = vec![];
+    for line in input.lines() {
+        let (a, b) = line.split_once("~").unwrap();
+        let start: XYZ = a.split(",").map(|s| s.parse().unwrap()).collect_tuple().unwrap();
+        let end: XYZ = b.split(",").map(|s| s.parse().unwrap()).collect_tuple().unwrap();
+        bricks.push(Brick { start, end });
+    }
+
+    bricks.sort_by(|a, b| a.start.2.cmp(&b.start.2));
+    bricks
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let mut bricks = parse(input);
+    let highest_brick = bricks.last().unwrap();
+    let max_z = max(highest_brick.start.2, highest_brick.end.2);
+
+    // This should probably be a vec of hashset of all the positions, not just start/end positions
+    let mut layers: Vec<Vec<XY>> = vec![vec![]; max_z];
+    for i in 0..bricks.len() {
+        for z in bricks[i].start.2..=bricks[i].end.2 {
+            layers[z - 1].push((bricks[i].start.0, bricks[i].start.1));
+        }
+    }
+
+    let mut settled = false;
+    while !settled {
+        settled = true;
+        for brick in bricks.iter_mut() {
+            if brick.start.2 == 1 || brick.end.2 == 1 {
+                continue;
+            }
+
+            // Update this:
+            // 1) iterate over the positions in the layer
+            // 2) for each position, check each component to see if it's contained by the brick's start/end range for that component
+            // 3) if it is, skip this brick
+            // 4) otherwise, update the brick position, add the positions it occupies to the new layer, and remove its positions from the layer it was in
+            if !layers[brick.start.2 - 2].contains(&(brick.start.0, brick.start.1)) {
+                brick.start.2 -= 1;
+                brick.end.2 -= 1;
+                settled = false;
+            }
+        }
+    }
+
+    None
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, None);
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, None);
+    }
+}