day14 solution 1

1 files changed, 100 insertions, 0 deletions

diff --git a/src/bin/day14.rs b/src/bin/day14.rs
new file mode 100644
index 0000000..6c3f0df
--- /dev/null
+++ b/src/bin/day14.rs
@@ -0,0 +1,100 @@
+use std::collections::HashSet;
+
+static DAY: u8 = 14;
+
+fn main() {
+    let input = advent::read_lines(DAY);
+    println!("{DAY}a: {}", total_load(&input));
+    println!("{DAY}b: {}", 0);
+}
+
+#[derive(PartialEq, Eq, Hash, Clone, Copy)]
+struct Position {
+    x: isize,
+    y: isize,
+}
+
+struct Map {
+    round_rocks: HashSet<Position>,
+    cube_rocks: HashSet<Position>,
+    _width: isize,
+    height: isize,
+}
+
+impl Map {
+    fn new(input: &[String]) -> Map {
+        let mut round_rocks = HashSet::new();
+        let mut cube_rocks = HashSet::new();
+
+        for (y, line) in input.iter().enumerate() {
+            for (x, rock) in line.chars().enumerate() {
+                let pos = Position { x: x as isize, y: y as isize };
+                match rock {
+                    '#' => { cube_rocks.insert(pos); }
+                    'O' => { round_rocks.insert(pos); }
+                    _ => {},
+                }
+            }
+        }
+
+        Map { round_rocks, cube_rocks, _width: input[0].len() as isize, height: input.len() as isize }
+    }
+
+    fn tilt(&mut self) {
+        loop {
+            let mut round_rocks = self.round_rocks.clone();
+
+            for rock in &self.round_rocks {
+                round_rocks.remove(rock);
+                let mut new_pos = *rock;
+                for y in (0 .. rock.y).rev() {
+                    let pos = Position { x: rock.x, y };
+                    if self.cube_rocks.contains(&pos) || round_rocks.contains(&pos) {
+                        break;
+                    }
+                    new_pos = pos;
+                }
+                round_rocks.insert(new_pos);
+            }
+
+            if self.round_rocks == round_rocks {
+                break;
+            }
+            self.round_rocks = round_rocks;
+        }
+    }
+
+    fn load(&self) -> isize {
+        self.round_rocks.iter()
+                        .map(|rock| self.height - rock.y)
+                        .sum()
+    }
+}
+
+fn total_load(input: &[String]) -> isize {
+    let mut map = Map::new(input);
+    map.tilt();
+    map.load()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let input = [
+            "O....#....",
+            "O.OO#....#",
+            ".....##...",
+            "OO.#O....O",
+            ".O.....O#.",
+            "O.#..O.#.#",
+            "..O..#O..O",
+            ".......O..",
+            "#....###..",
+            "#OO..#....",
+        ].iter().map(|&x| String::from(x)).collect::<Vec<_>>();
+        assert_eq!(total_load(&input), 136);
+    }
+}