3 files changed, 62 insertions, 0 deletions
diff --git a/2024/22/.gitignore b/2024/22/.gitignore
new file mode 100644
index 0000000..ffc46fe
--- /dev/null
+++ b/2024/22/.gitignore
@@ -0,0 +1 @@
+puzzle-[12].py
diff --git a/2024/22/Makefile b/2024/22/Makefile
new file mode 100644
index 0000000..0a4e980
--- /dev/null
+++ b/2024/22/Makefile
@@ -0,0 +1 @@
+include ../../Makefiles/py.mk
diff --git a/2024/22/puzzles.py b/2024/22/puzzles.py
new file mode 100644
index 0000000..dff825f
--- /dev/null
+++ b/2024/22/puzzles.py
@@ -0,0 +1,60 @@
+#!/usr/bin/python3
+
+import collections
+from typing import Deque, Iterable
+
+
+type Diff = tuple[int, int, int, int]
+
+
+def main() -> None:
+	with open("input", "r") as f:
+		xs = map(int, f.readlines())
+
+	# START PART 1
+	print(sum(map(lastfrom, map(secrets, xs))))
+	# END PART 1 START PART 2
+	sums = collections.defaultdict(int)
+	for x in xs:
+		seen: set[Diff] = set()
+		dq: Deque[int] = collections.deque(maxlen=4)
+
+		gen = map(lastdigit, secrets(x))
+		last = next(gen)
+
+		for _ in range(3):
+			n = next(gen)
+			dq.append(n - last)
+			last = n
+
+		for n in gen:
+			dq.append(n - last)
+			if (t := tuple(dq)) not in seen:
+				seen.add(t)
+				sums[t] += n
+			last = n
+			dq.popleft()
+
+	print(max(sums.values()))
+	# END PART 2
+
+
+def secrets(n: int) -> int:
+	for _ in range(2000):
+		n = (n ^ n<<6)	& 0xFFFFFF
+		n = (n ^ n>>5)	& 0xFFFFFF
+		n = (n ^ n<<11) & 0xFFFFFF
+		yield n
+
+
+def lastdigit(n: int) -> int:
+	return n % 10
+
+
+def lastfrom[T](xs: Iterable[T]) -> T:
+	*_, x = xs
+	return x
+
+
+if __name__ == "__main__":
+	main()