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-rw-r--r--src/day18.rs76
1 files changed, 60 insertions, 16 deletions
diff --git a/src/day18.rs b/src/day18.rs
index 636b342..ffb25ad 100644
--- a/src/day18.rs
+++ b/src/day18.rs
@@ -1,8 +1,14 @@
-fn adjescent(p: &(usize,usize,usize)) -> Vec<(usize,usize,usize)> {
+fn adjescent(p: &(usize,usize,usize), mx:usize) -> Vec<(usize,usize,usize)> {
let mut v = vec![];
- v.push((p.0+1,p.1,p.2));
- v.push((p.0,p.1+1,p.2));
- v.push((p.0,p.1,p.2+1));
+ if p.0+1 < mx {
+ v.push((p.0+1,p.1,p.2));
+ }
+ if p.1+1 < mx {
+ v.push((p.0,p.1+1,p.2));
+ }
+ if p.2+1 < mx {
+ v.push((p.0,p.1,p.2+1));
+ }
if p.0 > 0 {
v.push((p.0-1,p.1,p.2));
}
@@ -15,6 +21,31 @@ fn adjescent(p: &(usize,usize,usize)) -> Vec<(usize,usize,usize)> {
v
}
+#[derive(Debug,PartialEq)]
+enum State {Rock,Unknown,OutsideAir}
+
+fn mark_outside(grid: &mut Vec<Vec<Vec<State>>>, curr: &(usize,usize,usize), mx: usize) {
+ for cell in adjescent(curr, mx) {
+ if let State::Unknown = grid[cell.0][cell.1][cell.2] {
+ grid[cell.0][cell.1][cell.2] = State::OutsideAir;
+ mark_outside(grid, &cell, mx);
+ }
+ }
+}
+
+fn surface_area(grid: &Vec<Vec<Vec<State>>>, cubes: &Vec<(usize,usize,usize)>, mx: usize) -> usize {
+ let surface_area: usize = cubes.iter().map(|cube| {
+ let mut score = 6;
+ for p in adjescent(cube, mx) {
+ if let State::Rock = grid[p.0][p.1][p.2] {
+ score -= 1;
+ }
+ }
+ score
+ }).sum();
+ surface_area
+}
+
pub fn run(input:String) {
let cubes = input.lines()
.map(|line| {
@@ -25,20 +56,33 @@ pub fn run(input:String) {
(res[0], res[1], res[2])
}).collect::<Vec<(usize,usize,usize)>>();
let mx: usize = cubes.iter().map(|t| {vec![t.0, t.1, t.2]}).flatten().max().unwrap() + 3;
- // Allocate a 3d space..
- let mut grid: Vec<Vec<Vec<bool>>> = (0..mx).map(|_| {(0..mx).map(|_| {(0..mx).map(|_| {false}).collect()}).collect()}).collect();
+ // Allocate a 3d space, and mark the rocky cubes
+ let mut grid: Vec<Vec<Vec<State>>> = (0..mx).map(|_| {(0..mx).map(|_| {(0..mx).map(|_| {State::Unknown}).collect()}).collect()}).collect();
for cube in cubes.iter() {
- grid[cube.0][cube.1][cube.2] = true;
+ grid[cube.0][cube.1][cube.2] = State::Rock;
}
- // Now count cubes. Each contributes 6,minus number of connections
- let surface_area: usize = cubes.iter().map(|cube| {
- let mut score = 6;
- for p in adjescent(cube) {
- if grid[p.0][p.1][p.2] {
- score -= 1;
+ // Now count cubes. Each contributes 6, minus number of adjescent rocky cubes
+
+ println!("Day 18 pt1: {}", surface_area(&grid, &cubes, mx));
+ // So... how can I remove pockets of air to get the _outside_ surface area?
+ // ans; fill in the inside areas!
+ // pick a spot definitely on the outside;; iterate out until all the outside is marked.
+ // Anything remaining is pockets, fill it in, re-calculate the outside surface area.
+ grid[0][0][0] = State::OutsideAir;
+ mark_outside(&mut grid, &(0,0,0), mx);
+ // All remaining Unknown cells are air pockets, fill 'em in
+ for x in 0..mx {
+ for y in 0..mx {
+ for z in 0..mx {
+ match grid[x][y][z] {
+ State::Unknown => {
+ grid[x][y][z] = State::Rock;
+ },
+ _ => ()
+ };
}
}
- score
- }).sum();
- println!("Day 18: {}", surface_area);
+ }
+ // recalculate the surface area
+ println!("Day 18 pt2: {}", surface_area(&grid, &cubes, mx));
} \ No newline at end of file