import copy


def load(filename):
	with open(filename, "r", encoding="utf-8") as f:
		return [int(x) for x in f]


def calc_builtin(adapters):
	return max(adapters) + 3


def calc_diffs(adapters):
	wall = 0
	builtin = calc_builtin(adapters)
	adapters = sorted(adapters)
	adapters.insert(0, 0)
	adapters.append(builtin)
	adapters += [wall, builtin]

	d1 = 0
	d2 = 0
	d3 = 0
	sa = sorted(adapters)
	for x in range(0, len(sa) - 1):
		a = sa[x]
		b = sa[x+1]
		d = b - a
		if d == 1:
			d1 += 1
		elif d == 2:
			d2 += 1
		elif d == 3:
			d3 += 1

	return d1, d2, d3


def is_compatible(a, b):
	return abs(a - b) <= 3


def calc_arrangements(adapters, wall, builtin):
	return _calc(sorted(adapters), [wall], builtin)

def _calc(adapters, arranged, builtin):
	a = arranged[-1]
	b = adapters.pop(0)
	while is_compatible(a, b):
		if not adapters:
			if is_compatible(b, builtin):
				yield arranged + [b, builtin]
			return

		cadapters = copy.deepcopy(adapters)
		carranged = copy.deepcopy(arranged)
		carranged.append(b)
		yield from _calc(cadapters, carranged, builtin)

		b = adapters.pop(0)


assert calc_builtin([3, 6, 9]) == 12

adapters = load("test1.txt")
d1, _, d3 = calc_diffs(adapters)
assert d1 == 7
assert d3 == 5

adapters = load("test2.txt")
d1, d2, d3 = calc_diffs(adapters)
assert d1 == 22
assert d3 == 10
print(d1, d2, d3)

adapters = load("data.txt")
d1, _, d3 = calc_diffs(adapters)
print(f"1: Answer is {d1 * d3}")

##############################################################################

assert d1*d3 == 2450, "Task 1"

adapters = load("test1.txt")
bi = calc_builtin(adapters)
arrangements = list(calc_arrangements(adapters, 0, bi))
assert [0, 1, 4, 5, 6, 7, 10, 11, 12, 15, 16, 19, 22] in arrangements
assert [0, 1, 4, 5, 6, 7, 10, 12, 15, 16, 19, 22] in arrangements
assert [0, 1, 4, 5, 7, 10, 11, 12, 15, 16, 19, 22] in arrangements
assert [0, 1, 4, 5, 7, 10, 12, 15, 16, 19, 22] in arrangements
assert [0, 1, 4, 6, 7, 10, 11, 12, 15, 16, 19, 22] in arrangements
assert [0, 1, 4, 6, 7, 10, 12, 15, 16, 19, 22] in arrangements
assert [0, 1, 4, 7, 10, 11, 12, 15, 16, 19, 22] in arrangements
assert [0, 1, 4, 7, 10, 12, 15, 16, 19, 22] in arrangements

adapters = load("test2.txt")
bi = calc_builtin(adapters)
arrangements = list(calc_arrangements(adapters, 0, bi))
assert [0, 1, 2, 3, 4, 7, 8, 9, 10, 11, 14, 17, 18, 19, 20, 23, 24, 25, 28, 31, 32, 33, 34, 35, 38, 39, 42, 45, 46, 47, 48, 49, 52] in arrangements
assert [0, 1, 2, 3, 4, 7, 8, 9, 10, 11, 14, 17, 18, 19, 20, 23, 24, 25, 28, 31, 32, 33, 34, 35, 38, 39, 42, 45, 46, 47, 49, 52] in arrangements
assert [0, 1, 2, 3, 4, 7, 8, 9, 10, 11, 14, 17, 18, 19, 20, 23, 24, 25, 28, 31, 32, 33, 34, 35, 38, 39, 42, 45, 46, 48, 49, 52] in arrangements
assert [0, 1, 2, 3, 4, 7, 8, 9, 10, 11, 14, 17, 18, 19, 20, 23, 24, 25, 28, 31, 32, 33, 34, 35, 38, 39, 42, 45, 46, 49, 52] in arrangements
assert [0, 1, 2, 3, 4, 7, 8, 9, 10, 11, 14, 17, 18, 19, 20, 23, 24, 25, 28, 31, 32, 33, 34, 35, 38, 39, 42, 45, 47, 48, 49, 52] in arrangements
assert [0, 3, 4, 7, 10, 11, 14, 17, 20, 23, 25, 28, 31, 34, 35, 38, 39, 42, 45, 46, 48, 49, 52] in arrangements
assert [0, 3, 4, 7, 10, 11, 14, 17, 20, 23, 25, 28, 31, 34, 35, 38, 39, 42, 45, 46, 49, 52] in arrangements
assert [0, 3, 4, 7, 10, 11, 14, 17, 20, 23, 25, 28, 31, 34, 35, 38, 39, 42, 45, 47, 48, 49, 52] in arrangements
assert [0, 3, 4, 7, 10, 11, 14, 17, 20, 23, 25, 28, 31, 34, 35, 38, 39, 42, 45, 47, 49, 52] in arrangements
assert [0, 3, 4, 7, 10, 11, 14, 17, 20, 23, 25, 28, 31, 34, 35, 38, 39, 42, 45, 48, 49, 52] in arrangements
assert len(arrangements) == 19208

#adapters = load("data.txt")
#bi = calc_builtin(adapters)
#
#arrangements = calc_arrangements(adapters, 0, bi)
#c = 0
#for x in arrangements:
#	print(x)
#	c += 1
#
#print(f"2:Found {c} ways to connect.")