From cb2e955be75986a239fc44c6bccc6c72ff29715d Mon Sep 17 00:00:00 2001
From: Pavel Karateev <lancelote.du.lac@gmail.com>
Date: Sat, 14 Dec 2024 00:11:30 +0100
Subject: [PATCH] 2024 day 11 parts 2

---
 README.md                         |  2 +-
 src/year2024/day11b.py            | 26 ++++++++++++++++++++++++++
 tests/src/year2024/test_day11b.py |  8 ++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 src/year2024/day11b.py
 create mode 100644 tests/src/year2024/test_day11b.py

diff --git a/README.md b/README.md
index 3e20a49..33f8d61 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@
 - 2021 - ★★★★★ ★★★★★ ★★★★★ ★★★
 - 2022 - ★★★★★ ★★★★★ ★★★★★ ★☆
 - 2023 - ★★★★★ ★★★★★ ★★★★★ ★★★☆
-- 2024 - ★★★★★ ★★★★★ ☆
+- 2024 - ★★★★★ ★★★★★ ★
 
 ## How to use
 
diff --git a/src/year2024/day11b.py b/src/year2024/day11b.py
new file mode 100644
index 0000000..368041e
--- /dev/null
+++ b/src/year2024/day11b.py
@@ -0,0 +1,26 @@
+"""2024 - Day 11 Part 2: Plutonian Pebbles"""
+
+from functools import cache
+
+
+@cache
+def evolve(stone: int, generation: int) -> int:
+    if generation == 0:
+        return 1
+
+    if stone == 0:
+        return evolve(1, generation - 1)
+    elif len(str(stone)) % 2 == 0:
+        middle = len(str(stone)) // 2
+
+        left = int(str(stone)[:middle])
+        right = int(str(stone)[middle:])
+
+        return evolve(left, generation - 1) + evolve(right, generation - 1)
+    else:
+        return evolve(stone * 2024, generation - 1)
+
+
+def solve(task: str) -> int:
+    stones = [int(x) for x in task.split()]
+    return sum(evolve(stone, 75) for stone in stones)
diff --git a/tests/src/year2024/test_day11b.py b/tests/src/year2024/test_day11b.py
new file mode 100644
index 0000000..192e095
--- /dev/null
+++ b/tests/src/year2024/test_day11b.py
@@ -0,0 +1,8 @@
+"""2024 - Day 11 Part 2: Plutonian Pebbles"""
+
+from src.year2024.day11b import solve
+
+
+def test_solve():
+    task = "125 17"
+    assert solve(task) == 65601038650482