Make D8 more general

aoc/src/dev/ctsk/aoc/Grid.scala

@@ -4,6 +4,7 @@ case class Point(x: Int, y: Int):
   def +(o: Point): Point = Point(x + o.x, y + o.y)
   def -(o: Point): Point = Point(x - o.x, y - o.y)
   def *(n: Int): Point = Point(n * x, n * y)
+  def reduce: Point = { val g = gcd(x.abs, y.abs); Point(x / g, y / g) }
 
 enum Direction:
   case Up, Right, Down, Left

aoc/src/dev/ctsk/aoc/Utils.scala

@@ -1,3 +1,4 @@
 package dev.ctsk.aoc
 
-
+def gcd(a: Int, b: Int): Int =
+  if b == 0 then a else gcd(b, a % b)

aoc/src/dev/ctsk/aoc/days/Day08.scala

@@ -16,7 +16,7 @@ object Day08 extends Solver(8):
 
     def antinodes(a: Point, b: Point): Iterator[Point] =
       def it(a: Point, b: Point) =
-        Iterator.iterate(a)(_ + a - b).takeWhile(grid.contains)
+        Iterator.iterate(a)(_ + (a - b).reduce).takeWhile(grid.contains)
       it(a, b) ++ it(b, a)
 
     def part1: Int =