Added alternative.

Author: r0f1

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)|Adapter Array|[py](/day10/main.py)|
+|[10](https://adventofcode.com/2020/day/10)|Adapter Array|[py](/day10/main.py), [alt](/day10/alt.py)|
 |[11](https://adventofcode.com/2020/day/11)|-|-|
 |[12](https://adventofcode.com/2020/day/12)|-|-|
 |[13](https://adventofcode.com/2020/day/13)|-|-|

day10/alt.py

@@ -0,0 +1,10 @@
+import numpy as np
+
+with open("input.txt") as file:
+    d = sorted(map(int, file.readlines()))
+
+df = np.array([1] + list(np.diff(d)) + [3])
+rle = np.diff([-1] + [i for i, x in enumerate(np.diff(df)) if x != 0] + [len(df)-1])
+m = [2**x - sum("000" in bin(y)[2:].zfill(x) for y in range(2**x)) for x in range(max(rle) + 1)]
+print((df == 1).sum()*(df == 3).sum())
+print(np.prod([m[x-1] for i, x in enumerate(rle) if i % 2 == 0]))

day10/main.py

@@ -5,13 +5,8 @@
     numbers = sorted([int(x) for x in f])
 
 k = np.diff(numbers)
-print((1+len(k[k == 1])) * (1+len(k[k == 3])))
+print((1+(k == 1).sum()) * (1+(k == 3).sum()))
 
-# 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))
+combinations = {2: 2, 3: 4, 4: 7}
+print(np.prod([combinations[e] for e in cands]))