Day 10

day10/part2.py

@@ -0,0 +1,44 @@
+import numpy as np
+import operator
+from functools import reduce
+
+lines = sorted(int(x.strip()) for x in open("input.txt"))
+
+lines.append(lines[-1]+3)
+lines.insert(0, 0)
+lines = np.array(lines)
+
+diff = lines[1:] - lines[:-1]
+
+one_count = 0
+possibilities = []
+
+one_cache = {}
+
+
+def count_one_possibilities(one_cnt: int):
+    if one_cnt not in one_cache:
+        if one_cnt <= 1:
+            one_cache[one_cnt] = 1
+        else:
+            one_cache[one_cnt] = sum(count_one_possibilities(less) for less in range(max(0, one_cnt - 3), one_cnt))
+    return one_cache[one_cnt]
+
+
+def prod(iterable):
+    return reduce(operator.mul, iterable, 1)
+
+
+# only 3 and 1 differences are available
+# 3 has to be taken / calculate possibilities for 1 hops
+for num in diff:
+    if num == 1:
+        one_count += 1
+    elif num == 3:
+        factor = count_one_possibilities(one_count)
+        if factor > 1:
+            possibilities.append(factor)
+        one_count = 0
+
+print(prod(possibilities))  # 64793042714624
+print(one_cache)  # {0: 1, 1: 1, 2: 2, 3: 4, 4: 7}