Implement day 11 solver

puzzles/11.py

@@ -0,0 +1,55 @@
+from functools import cache
+from math import log
+from typing import override
+from unittest import TestCase
+
+from puzzles._solver import Solver
+
+
+class DayElevenSolver(Solver):
+    stones: tuple[int, ...]
+
+    @override
+    def __init__(self, puzzle_input: str):
+        self.stones = tuple(map(int, puzzle_input.strip().split(" ")))
+
+    @override
+    def solve_p1(self) -> int:
+        return sum(sum_descendants(stone, 25) for stone in self.stones)
+
+    @override
+    def solve_p2(self) -> int:
+        return sum(sum_descendants(stone, 75) for stone in self.stones)
+
+
+@cache
+def sum_descendants(stone: int, blinks: int) -> int:
+    if blinks == 0:
+        return 1
+
+    if stone == 0:
+        return sum_descendants(1, blinks - 1)
+
+    digit_len = int(log(stone, 10)) + 1
+    if digit_len % 2 == 0:
+        left_digits, right_digits = divmod(stone, 10 ** (digit_len // 2))
+        return sum_descendants(left_digits, blinks - 1) + sum_descendants(
+            right_digits, blinks - 1
+        )
+
+    return sum_descendants(stone * 2024, blinks - 1)
+
+
+class TestDayElevenSolver(TestCase):
+    def test_sum_descendants(self):
+        self.assertEqual(sum_descendants(0, 1), 1)
+        self.assertEqual(sum_descendants(17, 1), 2)
+        self.assertEqual(sum_descendants(125, 4), 3)
+
+    def test_parse(self):
+        solver = DayElevenSolver("123 4 56\n")
+        self.assertEqual(solver.stones, (123, 4, 56))
+
+    def test_solve_p1(self):
+        solver = DayElevenSolver("125 17\n")
+        self.assertEqual(solver.solve_p1(), 55312)