From 92bd85e1dd8a388cc28b42c5ae2417b7dc28726f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mika=C3=ABl=20Capelle?= <capelle.mikael@gmail.com>
Date: Wed, 11 Dec 2024 07:13:28 +0100
Subject: [PATCH] 2024 day 11.

---
 src/holt59/aoc/2024/day11.py                | 24 ++++++++++++++++++++-
 src/holt59/aoc/inputs/holt59/2024/day11.txt |  1 +
 src/holt59/aoc/inputs/tests/2024/day11.txt  |  1 +
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/src/holt59/aoc/2024/day11.py b/src/holt59/aoc/2024/day11.py
index 07e201e..fea35bf 100644
--- a/src/holt59/aoc/2024/day11.py
+++ b/src/holt59/aoc/2024/day11.py
@@ -1,7 +1,29 @@
+from functools import cache
 from typing import Any, Iterator
 
 from ..base import BaseSolver
 
 
+@cache
+def blink_one_stone(stone: int, round: int) -> int:
+    if round == 0:
+        return 1
+
+    if stone == 0:
+        return blink_one_stone(1, round - 1)
+
+    if len((stone_s := str(stone))) % 2 == 0:
+        n = len(stone_s)
+        return blink_one_stone(int(stone_s[: n // 2]), round - 1) + blink_one_stone(
+            int(stone_s[n // 2 :]), round - 1
+        )
+
+    return blink_one_stone(stone * 2024, round - 1)
+
+
 class Solver(BaseSolver):
-    def solve(self, input: str) -> Iterator[Any]: ...
+    def solve(self, input: str) -> Iterator[Any]:
+        stones = list(map(int, input.split()))
+
+        yield sum(blink_one_stone(stone, 25) for stone in stones)
+        yield sum(blink_one_stone(stone, 75) for stone in stones)
diff --git a/src/holt59/aoc/inputs/holt59/2024/day11.txt b/src/holt59/aoc/inputs/holt59/2024/day11.txt
index e69de29..4c7941d 100644
--- a/src/holt59/aoc/inputs/holt59/2024/day11.txt
+++ b/src/holt59/aoc/inputs/holt59/2024/day11.txt
@@ -0,0 +1 @@
+2 77706 5847 9258441 0 741 883933 12
diff --git a/src/holt59/aoc/inputs/tests/2024/day11.txt b/src/holt59/aoc/inputs/tests/2024/day11.txt
index e69de29..9b26c84 100644
--- a/src/holt59/aoc/inputs/tests/2024/day11.txt
+++ b/src/holt59/aoc/inputs/tests/2024/day11.txt
@@ -0,0 +1 @@
+125 17