2024 day 11

Author: Peter554

2024/python/data/day11/example.txt

@@ -0,0 +1 @@
+125 17

2024/python/data/day11/input.txt

@@ -0,0 +1 @@
+773 79858 0 71 213357 2937 1 3998391

2024/python/src/aoc2024/day11.py

@@ -0,0 +1,33 @@
+import functools
+from pathlib import Path
+
+
+def part_1(input: Path) -> int:
+    stones = list(map(int, input.read_text().strip().split()))
+    return sum(count_stones(stone, 25) for stone in stones)
+
+
+def part_2(input: Path) -> int:
+    stones = list(map(int, input.read_text().strip().split()))
+    return sum(count_stones(stone, 75) for stone in stones)
+
+
+@functools.cache
+def count_stones(stone: int, blinks_remaining: int) -> int:
+    if blinks_remaining == 0:
+        return 1
+
+    if stone == 0:
+        return count_stones(1, blinks_remaining - 1)
+
+    str_stone = str(stone)
+    if len(str_stone) % 2 == 0:
+        return count_stones(
+            int(str_stone[: len(str_stone) // 2]),
+            blinks_remaining - 1,
+        ) + count_stones(
+            int(str_stone[len(str_stone) // 2 :]),
+            blinks_remaining - 1,
+        )
+
+    return count_stones(stone * 2024, blinks_remaining - 1)

2024/python/tests/test_day11.py

@@ -0,0 +1,14 @@
+from pathlib import Path
+
+from aoc2024 import day11
+
+DATA_DIR = Path(__file__).parent.parent / "data/day11"
+
+
+def test_part_1():
+    assert day11.part_1(DATA_DIR / "example.txt") == 55312
+    assert day11.part_1(DATA_DIR / "input.txt") == 199982
+
+
+def test_part_2():
+    assert day11.part_2(DATA_DIR / "input.txt") == 237149922829154

README.md

@@ -18,8 +18,8 @@ Updated 2026-01-03.
 | **2021**   | **50/50** 🌟 | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        |
 | **2022**   | **50/50** 🌟 | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        |
 | **2023**   | 42/50            | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | 🟩        | ⬜        | 🟩        | ⬜        | ⬜        | ⬜        |
-| **2024**   | 20/50            | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        |
+| **2024**   | 22/50            | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩        | 🟩        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        | ⬜        |
 | **2025**   | **24/24** 🌟 | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩       | 🟩        | 🟩        | 🟩        | ⬛        | ⬛        | ⬛        | ⬛        | ⬛        | ⬛        | ⬛        | ⬛        | ⬛        | ⬛        | ⬛        | ⬛        | ⬛        |
 
-Total stars: 334/524
+Total stars: 336/524
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