1 files changed, 57 insertions, 0 deletions
diff --git a/20/py/d03.py b/20/py/d03.py
new file mode 100644
index 0000000..40b6b6c
--- /dev/null
+++ b/20/py/d03.py
@@ -0,0 +1,57 @@
+#!/usr/bin/env python3
+import sys
+
+
+def pt1(_in):
+    squares = set()
+    trees = set()
+    for y in range(len(_in)):
+        for x in range(len(_in[y])):
+            if _in[y][x] == ".":
+                squares.add((x, y))
+            else:
+                trees.add((x, y))
+    h = len(_in)
+    w = len(_in[0]) - 1 # \n
+    amount = 0
+    x, y = 0, 0
+    while y < h:
+        x += 3
+        y += 1
+        if (x % w, y) in trees:
+            amount += 1
+    return amount
+
+
+def pt2(_in):
+    squares = set()
+    trees = set()
+    for y in range(len(_in)):
+        for x in range(len(_in[y])):
+            if _in[y][x] == ".":
+                squares.add((x, y))
+            else:
+                trees.add((x, y))
+    h = len(_in)
+    w = len(_in[0]) - 1 # \n
+    amounts = []
+    for slope in [(1,1), (3,1), (5,1), (7,1), (1,2)]:
+        amount = 0
+        x, y = 0, 0
+        while y < h:
+            x += slope[0]
+            y += slope[1]
+            if (x % w, y) in trees:
+                amount += 1
+        amounts.append(amount)
+    s = 1
+    for a in amounts:
+        s *= a
+    return s
+
+
+if __name__ == "__main__":
+    input = open("../input/03", "r").readlines()
+    #input = [line for line in sys.stdin]
+    print(pt1(input))
+    print(pt2(input))