day 10

r0f1 · r0f1 · commit 050183ddcae5 · 2020-12-10T09:46:13.000+01:00
diff --git a/README.md b/README.md
@@ -11,7 +11,7 @@
 |[07](https://adventofcode.com/2020/day/7)|Handy Haversacks|[py](/day07/main.py), [alt](/day07/alt.py)|
 |[08](https://adventofcode.com/2020/day/8)|Handheld Halting|[py](/day08/main.py)|
 |[09](https://adventofcode.com/2020/day/9)|Encoding Error|[py](/day09/main.py)|
-|[10](https://adventofcode.com/2020/day/10)|-|-|
+|[10](https://adventofcode.com/2020/day/10)|Adapter Array|[py](/day10/main.py)|
 |[11](https://adventofcode.com/2020/day/11)|-|-|
 |[12](https://adventofcode.com/2020/day/12)|-|-|
 |[13](https://adventofcode.com/2020/day/13)|-|-|
diff --git a/day10/main.py b/day10/main.py
@@ -0,0 +1,17 @@
+import numpy as np
+from more_itertools import run_length
+
+with open("input.txt") as f:
+    numbers = sorted([int(x) for x in f])
+
+k = np.diff(numbers)
+print((1+len(k[k == 1])) * (1+len(k[k == 3])))
+
+# 1 --> ignore
+# 2 --> 1, 0 (2)
+# 3 --> 1 1, 1 0, 0 1, 0 0 (4)
+# 4 --> 1 1 1, 1 0 0, 0 1 0, 0 0 1, 1 1 0, 1 0 1, 0 1 1 (7)
+cands = [e for i, e in run_length.encode(np.diff([0]+numbers)) if i == 1 and e > 1]
+t = {2: 2, 3: 4, 4: 7}
+transformed = [t[e] for e in cands]
+print(np.prod(transformed))
