From be938144bf314f8b3cc3fb784d6b26233c13480f Mon Sep 17 00:00:00 2001
From: Sebastian Seedorf <mail@sebse.de>
Date: Thu, 10 Dec 2020 15:17:09 +0100
Subject: [PATCH] Day 10

---
 day10/input.txt | 102 ++++++++++++++++++++++++++++++++++++++++++++++++
 day10/part1.py  |  14 +++++++
 day10/part2.py  |  44 +++++++++++++++++++++
 3 files changed, 160 insertions(+)
 create mode 100644 day10/input.txt
 create mode 100644 day10/part1.py
 create mode 100644 day10/part2.py

diff --git a/day10/input.txt b/day10/input.txt
new file mode 100644
index 0000000..5746f73
--- /dev/null
+++ b/day10/input.txt
@@ -0,0 +1,102 @@
+103
+131
+121
+151
+118
+12
+7
+2
+90
+74
+160
+58
+15
+83
+153
+140
+166
+1
+148
+33
+165
+39
+100
+135
+68
+77
+25
+9
+54
+94
+101
+55
+141
+22
+97
+35
+57
+117
+102
+64
+109
+114
+56
+51
+125
+82
+154
+142
+155
+45
+75
+158
+120
+5
+19
+61
+34
+128
+106
+88
+84
+137
+96
+136
+27
+6
+21
+89
+69
+162
+112
+127
+119
+161
+38
+42
+134
+20
+81
+48
+73
+87
+26
+95
+146
+113
+76
+32
+70
+8
+18
+67
+124
+80
+93
+29
+126
+147
+28
+152
+145
+159
diff --git a/day10/part1.py b/day10/part1.py
new file mode 100644
index 0000000..eb8a8df
--- /dev/null
+++ b/day10/part1.py
@@ -0,0 +1,14 @@
+import numpy as np
+
+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]
+unique, counts = np.unique(diff, return_counts=True)
+cnt = dict(zip(unique, counts))
+
+print(cnt)
+print(cnt[1]*cnt[3])
diff --git a/day10/part2.py b/day10/part2.py
new file mode 100644
index 0000000..b2edb2d
--- /dev/null
+++ b/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}