From 36094741a5a60c6499fb54961eb245b9823e64be Mon Sep 17 00:00:00 2001
From: Christoph Stahl <christoph.stahl@uni-dortmund.de>
Date: Thu, 14 Dec 2023 09:20:08 +0100
Subject: [PATCH] Forgot to commit Day13

---
 aoc/day13.py | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 aoc/day13.py

diff --git a/aoc/day13.py b/aoc/day13.py
new file mode 100644
index 0000000..2ca004e
--- /dev/null
+++ b/aoc/day13.py
@@ -0,0 +1,90 @@
+from __future__ import annotations
+from array import array
+from typing import TypeAlias
+from itertools import groupby, islice
+
+from .aoc import Aoc2, AocSameParser
+from .day11 import Matrix
+
+
+P1: TypeAlias = list[Matrix]
+
+
+class Day13(AocSameParser[P1], Aoc2[P1, P1]):
+    def parseinput(self, inpt: str) -> P1:
+        fields = inpt.split("\n\n")
+
+        return [Matrix(group) for group in fields]
+
+    @staticmethod
+    def check_horiz(m: Matrix, max_diffs: int) -> int | None:
+        rows = list(m.iter_rows())
+
+        nr_rows = len(rows)
+
+        for x in range(1, nr_rows):
+            y = 0
+            if x > nr_rows / 2:
+                y = x + x - nr_rows
+
+            diff = Day13.diff_lines(rows[y:x], list(reversed(rows[x : x + x - y])))
+            if diff == max_diffs:
+                return x
+
+        return None
+
+    @staticmethod
+    def check_vert(m: Matrix, max_diffs: int) -> int | None:
+        cols = list(m.iter_cols())
+
+        nr_cols = len(cols)
+
+        for x in range(1, nr_cols):
+            y = 0
+            if x > nr_cols / 2:
+                y = x + x - nr_cols
+
+            diff = Day13.diff_lines(cols[y:x], list(reversed(cols[x : x + x - y])))
+
+            if diff == max_diffs:
+                return x
+
+        return None
+
+    @staticmethod
+    def diff_lines(a: list[array[str]], b: list[array[str]]) -> int:
+        return sum(map(lambda x, y: Day13.diff_line(x, y), a, b))
+
+    @staticmethod
+    def diff_line(a: array[str], b: array[str]) -> int:
+        return sum(map(lambda x, y: x != y, a, b))
+
+    @staticmethod
+    def compute(inpt: P1, max_diffs: int) -> int:
+        verts = 0
+        horiz = 0
+        for m in inpt:
+            mverts = Day13.check_vert(m, max_diffs)
+            if mverts is not None:
+                verts += mverts
+            else:
+                mhoriz = Day13.check_horiz(m, max_diffs)
+                if mhoriz is not None:
+                    horiz += mhoriz
+
+        return verts + 100 * horiz
+
+    def part1(self, inpt: P1) -> int:
+        return self.compute(inpt, 0)
+
+    def part2(self, inpt: P1) -> int:
+        return self.compute(inpt, 1)
+
+
+def main() -> None:
+    aoc = Day13(2023, 13, example_code_nr2=0)
+    aoc.run()
+
+
+if __name__ == "__main__":
+    main()