1 files changed, 52 insertions, 0 deletions
diff --git a/2015/18/puzzle-2.py b/2015/18/puzzle-2.py
new file mode 100755
index 0000000..9a998b8
--- /dev/null
+++ b/2015/18/puzzle-2.py
@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+
+
+def neighbours(data: list[list[str]], x: int, y: int) -> int:
+	acc = 0
+
+	for x1, y1 in [
+		(x - 1, y - 1),
+		(x - 1, y),
+		(x - 1, y + 1),
+		(x, y - 1),
+		(x, y + 1),
+		(x + 1, y - 1),
+		(x + 1, y),
+		(x + 1, y + 1),
+	]:
+		try:
+			if x1 >= 0 and y1 >= 0 and data[x1][y1] == "#":
+				acc += 1
+		except IndexError:
+			pass
+
+	return acc
+
+
+def simulate(data: list[list[str]]) -> list[list[str]]:
+	ndata = [["." for i in range(100)] for j in range(100)]
+
+	for i in range(100):
+		for j in range(100):
+			if (i, j) in [(0, 0), (0, 99), (99, 0), (99, 99)]:
+				ndata[i][j] = "#"
+			elif data[i][j] == "#" and neighbours(data, i, j) in [2, 3]:
+				ndata[i][j] = "#"
+			elif data[i][j] == "." and neighbours(data, i, j) == 3:
+				ndata[i][j] = "#"
+
+	return ndata
+
+def main() -> None:
+	with open("input", "r", encoding="utf-8") as f:
+		data = [list(l.strip()) for l in f.readlines()]
+	data[0][0], data[0][99], data[99][0], data[99][99] = "#", "#", "#", "#"
+
+	for i in range(100):
+		data = simulate(data)
+
+	print(sum(data[i].count("#") for i in range(100)))
+
+
+if __name__ == "__main__":
+	main()