6th day (brute force)

Author: majcn

data/examples/06.txt

@@ -0,0 +1,10 @@
+....#.....
+.........#
+..........
+..#.......
+.......#..
+..........
+.#..^.....
+........#.
+#.........
+......#...

src/bin/06.rs

@@ -0,0 +1,153 @@
+advent_of_code::solution!(6);
+
+use advent_of_code::maneatingape::hash::*;
+use advent_of_code::maneatingape::point::*;
+
+type Direction = Point;
+
+struct MapSize {
+    min_x: i32,
+    max_x: i32,
+    min_y: i32,
+    max_y: i32,
+}
+
+struct DataType {
+    position: Point,
+    direction: Direction,
+    obstructions: FastSet<Point>,
+    map_size: MapSize,
+}
+
+impl MapSize {
+    fn contains(&self, point: &Point) -> bool {
+        point.x >= self.min_x
+            && point.x <= self.max_x
+            && point.y >= self.min_y
+            && point.y <= self.max_y
+    }
+}
+
+fn parse_data(input: &str) -> DataType {
+    let my_direction = UP;
+    let mut my_position = Point::new(0, 0);
+    let mut obstructions = FastSet::new();
+
+    let height = input.lines().count();
+    let width = input.split_once("\n").unwrap().0.len();
+
+    for (y, line) in input.lines().enumerate() {
+        for (x, v) in line.bytes().enumerate() {
+            match v {
+                b'#' => {
+                    obstructions.insert(Point::new(x as i32, y as i32));
+                }
+                b'^' => {
+                    my_position = Point::new(x as i32, y as i32);
+                }
+                _ => {}
+            }
+        }
+    }
+
+    DataType {
+        position: my_position,
+        direction: my_direction,
+        obstructions,
+        map_size: MapSize {
+            min_x: 0,
+            max_x: width as i32 - 1,
+            min_y: 0,
+            max_y: height as i32 - 1,
+        },
+    }
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let data: DataType = parse_data(input);
+
+    let mut my_position = data.position;
+    let mut my_direction = data.direction;
+
+    let mut visit = FastSet::new();
+
+    loop {
+        visit.insert(my_position);
+
+        let next_position = my_position + my_direction;
+        if !data.map_size.contains(&next_position) {
+            break;
+        }
+
+        if data.obstructions.contains(&next_position) {
+            my_direction = my_direction.clockwise();
+        } else {
+            my_position = next_position;
+        }
+    }
+
+    let result = visit.len();
+
+    Some(result)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let data: DataType = parse_data(input);
+
+    let mut result = 0;
+
+    for y in data.map_size.min_y..=data.map_size.max_y {
+        for x in data.map_size.min_x..=data.map_size.max_x {
+            let new_obstruction = Point::new(x, y);
+
+            if data.position == new_obstruction || data.obstructions.contains(&new_obstruction) {
+                continue;
+            }
+
+            let mut visit: FastSet<(Point, Point)> = FastSet::new();
+
+            let mut my_position = data.position;
+            let mut my_direction = data.direction;
+
+            let stuck = loop {
+                if !visit.insert((my_position, my_direction)) {
+                    break true;
+                }
+
+                let next_position = my_position + my_direction;
+                if !data.map_size.contains(&next_position) {
+                    break false;
+                }
+
+                if new_obstruction == next_position || data.obstructions.contains(&next_position) {
+                    my_direction = my_direction.clockwise();
+                } else {
+                    my_position = next_position;
+                }
+            };
+
+            if stuck {
+                result += 1;
+            }
+        }
+    }
+
+    Some(result)
+}
+
+#[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, Some(41));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(6));
+    }
+}