Advent of Code 2017 day 3 problem solved in Python

aoc_2017_day_3.py

n = 361527

##########
# Part I #
##########

FRONTIER_SIZE_MULTIPLIER = 8

def distance(n):
	frame = 1
	max_num_in_frame = 1
	while max_num_in_frame < n:
		max_num_in_frame = sum(FRONTIER_SIZE_MULTIPLIER * i for i in range(frame + 1)) + 1
		frame += 1
	frame = frame - 1
	min_num_in_frame = max_num_in_frame - FRONTIER_SIZE_MULTIPLIER * frame + 1
	idx = (n - min_num_in_frame) % (frame * 2)
	min_dis_in_frame_idx = frame - 1
	dis = frame + abs(idx - min_dis_in_frame_idx)
	return dis

print(distance(n)) # 326

###########
# Part II #
###########

def first_larger(n):
	value = 1
	x, y = 0, 0
	cells = {(x, y): value}
	frame = 1
	# for lack of a better solution, we generate the numbers in
	# each frame of the spiral by moving around the previous one
	# until we know that the latest frame contains our number
	while value < n:
		# move right
		while x < frame:
			x += 1
			value = calculate_value(cells, x, y)
			cells[(x, y)] = value
		# move up
		while y < frame:
			y += 1
			value = calculate_value(cells, x, y)
			cells[(x, y)] = value
		# move left
		while x > -frame:
			x -= 1
			value = calculate_value(cells, x, y)
			cells[(x, y)] = value
		# move down
		while y > -frame:
			y -= 1
			value = calculate_value(cells, x, y)
			cells[(x, y)] = value
		# and finally move right again
		while x < frame:
			x += 1
			value = calculate_value(cells, x, y)
			cells[(x, y)] = value
		frame += 1
	return [v for v in sorted(cells.values()) if v > n][0]

def calculate_value(cells, x, y):
	return sum(cells.get(coords) for coords in neighbors(x, y) if cells.get(coords))

def neighbors(x, y):
	return (
		(x - 1, y + 1),
		(x, y + 1),
		(x + 1, y + 1),
		(x + 1, y),
		(x + 1, y - 1),
		(x, y - 1),
		(x - 1, y - 1),
		(x - 1, y)
	)

print(first_larger(n)) # 363010