import numpy as np


debug = False

def load_diagram(filename: str):
	# Read file as list of strings
	with open(filename, "r") as fp:
		data = fp.read().splitlines()
	
	data_arr = np.array(data, dtype=str)\
		.view("U1")\
		.reshape((len(data), -1))

	return data_arr

def print_diagram(diagram):
	for line in diagram:
		for char in line:
			print(char, end="")
		print()

def propagate_diagram(in_diagram, inplace=True):
	diagram = in_diagram.copy() if not inplace else in_diagram
	ylen = len(diagram)

	# Find start location
	y0 = 0
	x0, = np.where(diagram[y0] == "S")[0]

	# Emit starting beam
	diagram[y0 + 1, x0] = "|"
	splits_count = 0

	# Propagate the beams, starting with y = 2, as the y = 1 layer has our first beam
	for y in range(2, ylen):
		for x in np.where((diagram[y] == "^")&(diagram[y - 1] == "|"))[0]:
			# NOTE: I do not ever check whether carets are on the boundary.
			diagram[y, (x - 1, x + 1)] = "|"
			splits_count += 1
		for x in np.where((diagram[y] == ".")&(diagram[y - 1] == "|"))[0]:
			diagram[y, x] = "|"
		if debug:
			print_diagram(diagram)
			print()
	return splits_count

if __name__ == "__main__":
	test_diagram = load_diagram("testinput")
	assert propagate_diagram(test_diagram) == 21
	
	diagram = load_diagram("input")
	print(propagate_diagram(diagram))
	

def gnonkel(x, a):
	if x:
		a += 1
	
	# -----
	if x and y:
		a+=1
	elif x:
		a+=1