2023 day 13.

2023/day13.py

@@ -1,13 +1,43 @@
 import sys
-from collections import defaultdict
+from typing import Callable, Literal
-from dataclasses import dataclass
+
+
+def split(block: list[str], axis: Literal[0, 1], count: int) -> int:
+    n_iter = len(block) if axis == 0 else len(block[0])
+    n_check = len(block) if axis == 1 else len(block[0])
+
+    at: Callable[[int, int], str] = (
+        (lambda i, j: block[i][j]) if axis == 0 else (lambda i, j: block[j][i])
+    )
+
+    for i in range(n_iter - 1):
+        size = min(i + 1, n_iter - i - 1)
+        if (
+            sum(
+                at(i - s, j) != at(i + 1 + s, j)
+                for s in range(0, size)
+                for j in range(n_check)
+            )
+            == count
+        ):
+            return i + 1
+
+    return 0
+
+
+blocks = [block.splitlines() for block in sys.stdin.read().split("\n\n")]
 
-lines = sys.stdin.read().splitlines()
 
 # part 1
-answer_1 = ...
+answer_1 = sum(
+    split(block, axis=1, count=0) + 100 * split(block, axis=0, count=0)
+    for block in blocks
+)
 print(f"answer 1 is {answer_1}")
 
 # part 2
-answer_2 = ...
+answer_2 = sum(
+    split(block, axis=1, count=1) + 100 * split(block, axis=0, count=1)
+    for block in blocks
+)
 print(f"answer 2 is {answer_2}")

2023/tests/day13.txt

@@ -0,0 +1,15 @@
+#.##..##.
+..#.##.#.
+##......#
+##......#
+..#.##.#.
+..##..##.
+#.#.##.#.
+
+#...##..#
+#....#..#
+..##..###
+#####.##.
+#####.##.
+..##..###
+#....#..#