completed Day 3 part 2

Author: matthew-js-porter

day3/README.txt

@@ -48,4 +48,18 @@ The locations you'd check in the above example are marked here with O where ther
 .#..#...#.#.#..#...#.#.#..#...X.#.#..#...#.#.#..#...#.#.#..#...#.#  --->
 In this example, traversing the map using this slope would cause you to encounter 7 trees.
 
-Starting at the top-left corner of your map and following a slope of right 3 and down 1, how many trees would you encounter?
+Starting at the top-left corner of your map and following a slope of right 3 and down 1, how many trees would you encounter?
+
+--- Part Two ---
+Time to check the rest of the slopes - you need to minimize the probability of a sudden arboreal stop, after all.
+
+Determine the number of trees you would encounter if, for each of the following slopes, you start at the top-left corner and traverse the map all the way to the bottom:
+
+Right 1, down 1.
+Right 3, down 1. (This is the slope you already checked.)
+Right 5, down 1.
+Right 7, down 1.
+Right 1, down 2.
+In the above example, these slopes would find 2, 7, 3, 4, and 2 tree(s) respectively; multiplied together, these produce the answer 336.
+
+What do you get if you multiply together the number of trees encountered on each of the listed slopes?

day3/test_toboggan.py

@@ -21,6 +21,10 @@ def test_something(self):
         trees = toboggan.count_trees(self.route, (3,1))
         self.assertEqual(7, trees)
 
+    def test_count_trees_for_all_slopes(self):
+        trees = toboggan.calculate(self.route, [(1,1), (3,1), (5,1), (7,1), (1,2)])
+        self.assertEqual(336, trees)
+
 
 if __name__ == '__main__':
     unittest.main()

day3/toboggan.py

@@ -1,6 +1,13 @@
+import numpy
+
 TREE = '#'
 
 
+def calculate(route: str, slopes: list) -> int:
+    trees = [count_trees(route, slope) for slope in slopes]
+    return numpy.prod(trees)
+
+
 def count_trees(route: str, slope: tuple) -> int:
     parsed_route = parse(route)
     x = 0
@@ -23,4 +30,5 @@ def parse(route: str) -> list:
 
 if __name__ == '__main__':
     with open('input.txt') as data:
-        print(count_trees(data.read(), (3, 1)))
+        slopes = [(1,1), (3,1), (5,1), (7,1), (1,2)]
+        print(calculate(data.read(), slopes))

requirements.txt

@@ -0,0 +1 @@
+numpy