From b0c2ab4b946b0a89277b67a3033732cf6be888b0 Mon Sep 17 00:00:00 2001
From: Kees van Kempen <git@keesvankempen.nl>
Date: Sun, 7 Dec 2025 14:17:28 +0100
Subject: [PATCH] 2025(07): this is recursive death

---
 2025/07/part2.py | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 2025/07/part2.py

diff --git a/2025/07/part2.py b/2025/07/part2.py
new file mode 100644
index 0000000..f5d5ca5
--- /dev/null
+++ b/2025/07/part2.py
@@ -0,0 +1,61 @@
+import numpy as np
+from part1 import load_diagram, print_diagram
+
+debug = False
+
+def quantum_propagate_diagram(in_diagram):
+	diagram = in_diagram.copy()
+	ylen = len(diagram)
+
+	# Find start location
+	y0 = 0
+	x0, = np.where(diagram[y0] == "S")[0]
+
+	# Emit starting beam
+	diagram[y0 + 1, x0] = "|"
+	
+	# Propagate
+	worlds_count = quantum_propagate(x0, diagram[y0 + 2:])
+
+	return worlds_count
+
+def quantum_propagate(x, subdiagram):
+	ylen = len(subdiagram)
+	# print_diagram(subdiagram)
+	# print()
+	for y in range(0, ylen - 1):
+		if subdiagram[y, x] == ".":
+			# subdiagram[y, x] = "|"
+			if debug:
+				print("--- no split ---")
+				print_diagram(subdiagram)
+				print()
+		elif subdiagram[y, x] == "^":
+			# subdiagram[y, (x - 1, x + 1)] = "|"
+			# Split into two worlds, ignore what has happened before.
+			d1 = subdiagram[y + 1:]#.copy()
+			if debug:
+				print("--- split left ---")
+				print_diagram(d1)
+				print()
+			worlds_count = quantum_propagate(x - 1, d1)
+			d2 = subdiagram[y + 1:]#.copy()
+			if debug:
+				print("--- split right ---")
+				print_diagram(d2)
+				print()
+			worlds_count += quantum_propagate(x + 1, d2)
+			# print(worlds_count)
+			return worlds_count
+	# Reached the end, so this must be a world
+	if debug:
+		print("Reached end of world!")
+	return 1
+
+if __name__ == "__main__":
+	test_diagram = load_diagram("testinput")
+
+	assert quantum_propagate_diagram(test_diagram) == 40
+
+	diagram = load_diagram("input")
+	print(quantum_propagate_diagram(diagram))