AoC 2023 day 9, part 2

9/b.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+# Copyright 2023 Síle Ekaterin Liszka
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+# IN THE SOFTWARE.
+
+patterns = []
+
+with open('input.txt', mode='r') as f:
+	for line in f.readlines():
+		patterns.append(tuple([int(x) for x in line[:-1].split(' ')]))
+
+def diff(pattern):
+	return [pattern[x] - pattern[x - 1] for x in range(1, len(pattern))]
+
+pnext = {}
+for pattern in patterns:
+	diffs = [list(reversed(pattern))]
+	x = list(reversed(pattern))
+	while x := diff(x):
+		diffs.append(x)
+		if sum(x) == 0:
+			break
+
+	diffs.reverse()
+
+	for i in range(1, len(diffs)):
+		diffs[i].append(diffs[i - 1][-1] + diffs[i][-1])
+
+	pnext[pattern] = diffs[-1][-1]
+
+print(sum(pnext.values()))