From 023807a70112346efb6962d02945990319f09a63 Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Wed, 11 Dec 2024 08:51:32 +0100
Subject: [PATCH] Implement 2024 day 11

---
 2024/src/aoc/days/day11.py | 50 ++++++++++++++++++++++++++++++++++++++
 2024/tests/test_day11.py   |  7 ++++++
 2 files changed, 57 insertions(+)
 create mode 100644 2024/src/aoc/days/day11.py
 create mode 100644 2024/tests/test_day11.py

diff --git a/2024/src/aoc/days/day11.py b/2024/src/aoc/days/day11.py
new file mode 100644
index 0000000..cd0cb6c
--- /dev/null
+++ b/2024/src/aoc/days/day11.py
@@ -0,0 +1,50 @@
+import functools
+from collections import defaultdict
+
+from . import CombinedRunner
+
+
+@functools.cache
+def blink_num(num: int) -> tuple[int, ...]:
+    if num == 0:
+        return (1,)
+
+    num_str = str(num)
+    num_len = len(num_str)
+
+    if num_len % 2 == 0:
+        half = num_len // 2
+        return (int(num_str[:half]), int(num_str[half:]))
+
+    return (num * 2024,)
+
+
+def step(nums: dict[int, int]) -> dict[int, int]:
+    result = defaultdict(int)
+
+    for num, count in nums.items():
+        for transformed in blink_num(num):
+            result[transformed] += count
+
+    return result
+
+
+class DayRunner(CombinedRunner):
+    @classmethod
+    def run_both(cls, input: str) -> tuple[int, int]:
+        nums = [int(val) for val in input.strip().split(" ")]
+
+        counts = defaultdict(int)
+
+        for num in nums:
+            counts[num] += 1
+
+        for _ in range(25):
+            counts = step(counts)
+
+        part1 = sum(counts.values())
+
+        for _ in range(50):
+            counts = step(counts)
+
+        return part1, sum(counts.values())
diff --git a/2024/tests/test_day11.py b/2024/tests/test_day11.py
new file mode 100644
index 0000000..c839c1f
--- /dev/null
+++ b/2024/tests/test_day11.py
@@ -0,0 +1,7 @@
+from aoc.days.day11 import DayRunner
+
+SAMPLE = "125 17"
+
+
+def test_sample_part1() -> None:
+    assert DayRunner.part1(SAMPLE) == 55312