Day 12

aoc_cas/aoc2023/day12.py

@@ -0,0 +1,47 @@
+import re
+from functools import cache
+from typing import Iterator
+
+
+def resolve(line: str, groups: list[int]) -> int:
+    @cache
+    def inner(i0: int, i1: int) -> int:
+        if i1 == len(groups):
+            return 1 if "#" not in line[i0:] else 0
+        if i0 >= len(line):
+            return 0
+        pattern = re.compile(rf"[#?]{{{groups[i1]}}}([.?]|$)")
+        if pattern.match(line, pos=i0):
+            result = inner(i0 + groups[i1] + 1, i1 + 1)
+        else:
+            result = 0
+        if line[i0] != "#":
+            result += inner(i0 + 1, i1)
+        return result
+
+    return inner(0, 0)
+
+
+def unfold(line: str, groups: list[int]) -> tuple[str, list[int]]:
+    return "?".join([line] * 5), groups * 5
+
+
+def parse(data: str) -> Iterator[tuple[str, list[int]]]:
+    for line in data.splitlines():
+        springs, nums_str = line.split(" ")
+        nums = [int(c) for c in nums_str.split(",")]
+        yield springs, nums
+
+
+def part_a(data: str) -> int:
+    return sum(resolve(springs, nums) for springs, nums in parse(data))
+
+
+def part_b(data: str) -> int:
+    return sum(resolve(*unfold(*d)) for d in parse(data))
+
+
+if __name__ == "__main__":
+    from aoc_cas.util import solve_with_examples
+
+    solve_with_examples(year=2023, day=12)

tests/fixtures/2023/12.txt

@@ -0,0 +1,8 @@
+???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1
+21
+525152