Add day10

2019/day10-asteroids.py

@@ -0,0 +1,73 @@
+from dataclasses import dataclass
+from typing import Tuple, Set
+
+
+@dataclass
+class Asteroid:
+    x: int
+    y: int
+
+    def __hash__(self):
+        return hash((self.x, self.y))
+
+    @staticmethod
+    def square_length(a: "Asteroid", b: "Asteroid"):
+        return (b.x - a.x) * (b.x - a.x) + (b.y - a.y) * (b.y - a.y)
+
+    @staticmethod
+    def cross_product(a: "Asteroid", b: "Asteroid", c: "Asteroid"):
+        return (c.y - a.y) * (b.x - a.x) - (c.x - a.x) * (b.y - a.y)
+
+    @staticmethod
+    def dot_product(a: "Asteroid", b: "Asteroid", c: "Asteroid"):
+        return (c.x - a.x) * (b.x - a.x) + (c.y - a.y) * (b.y - a.y)
+
+    @staticmethod
+    def is_between(a: "Asteroid", b: "Asteroid", c: "Asteroid"):
+        """Check if c is between a and b."""
+        cross_product = Asteroid.cross_product(a, b, c)
+
+        # compare versus epsilon for floating point values, or != 0 if using integers
+        if abs(cross_product) != 0:
+            return False
+
+        dot_product = Asteroid.dot_product(a, b, c)
+        if dot_product < 0:
+            return False
+
+        squared_length_ba = Asteroid.square_length(a, b)
+        if dot_product > squared_length_ba:
+            return False
+
+        return True
+
+    def can_see(self, other: "Asteroid", asteroids: Set["Asteroid"]) -> bool:
+        for asteroid in asteroids:
+            if asteroid in [self, other]:
+                continue
+            if Asteroid.is_between(self, other, asteroid):
+                return False
+        return True
+
+
+def main():
+    asteroids = set()
+    with open("inputs/day10") as f:
+        for y, line in enumerate(f):
+            for x, pixel in enumerate(line):
+                if pixel == "#":
+                    asteroids.add(Asteroid(x, y))
+
+    max_visible = 0
+    for source in asteroids:
+        visible = 0
+        for destination in asteroids:
+            if destination != source and source.can_see(destination, asteroids):
+                visible += 1
+        if visible > max_visible:
+            max_visible = visible
+    print(max_visible)
+
+
+if __name__ == "__main__":
+    main()

2019/inputs/day10

@@ -0,0 +1,25 @@
+#..#.#.#.######..#.#...##
+##.#..#.#..##.#..######.#
+.#.##.#..##..#.#.####.#..
+.#..##.#.#..#.#...#...#.#
+#...###.##.##..##...#..#.
+##..#.#.#.###...#.##..#.#
+###.###.#.##.##....#####.
+.#####.#.#...#..#####..#.
+.#.##...#.#...#####.##...
+######.#..##.#..#.#.#....
+###.##.#######....##.#..#
+.####.##..#.##.#.#.##...#
+##...##.######..##..#.###
+...###...#..#...#.###..#.
+.#####...##..#..#####.###
+.#####..#.#######.###.##.
+#...###.####.##.##.#.##.#
+.#.#.#.#.#.##.#..#.#..###
+##.#.####.###....###..##.
+#..##.#....#..#..#.#..#.#
+##..#..#...#..##..####..#
+....#.....##..#.##.#...##
+.##..#.#..##..##.#..##..#
+.##..#####....#####.#.#.#
+#..#..#..##...#..#.#.#.##

2019/inputs/day10-ex1

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

2019/inputs/day10-ex2

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

2019/inputs/day10-ex3

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

2019/inputs/day10-ex4

@@ -0,0 +1,20 @@
+.#..##.###...#######
+##.############..##.
+.#.######.########.#
+.###.#######.####.#.
+#####.##.#.##.###.##
+..#####..#.#########
+####################
+#.####....###.#.#.##
+##.#################
+#####.##.###..####..
+..######..##.#######
+####.##.####...##..#
+.#####..#.######.###
+##...#.##########...
+#.##########.#######
+.####.#.###.###.#.##
+....##.##.###..#####
+.#.#.###########.###
+#.#.#.#####.####.###
+###.##.####.##.#..##