1 files changed, 35 insertions, 0 deletions
diff --git a/day3/day3.py b/day3/day3.py
new file mode 100644
index 0000000..716dc5e
--- /dev/null
+++ b/day3/day3.py
@@ -0,0 +1,35 @@
+from functools import reduce
+from itertools import islice
+
+
+def nth(iterable, n):
+    return next(islice(iter(iterable), n, n + 1))
+
+
+def mult(iterable):
+    return reduce(lambda x, y: x * y, iterable)
+
+
+def count_trees(data, right, down):
+    return [nth(row, right * idx % len(row)) for idx, row in enumerate(data[::down])].count("#")
+
+
+data = list(map(str.strip, open("input")))
+
+
+# Part 1
+down = 1
+right = 3
+print(count_trees(data, right, down))
+
+
+# Part 2
+slopes = [
+    # R, D
+    [1, 1],
+    [3, 1],
+    [5, 1],
+    [7, 1],
+    [1, 2],
+]
+print(mult([count_trees(data, right, down) for right, down in slopes]))