Advent of Code 2019 day 16 solution

aoc19-16.py

with open("input.txt") as f:
	inp = list(map(int, f.read()[::]))

def do_phase(lst):
	return [do_comp(lst, i) for i in range(len(lst))]

def get_mult(n, m):
	m += 1
	m %= 4 * n
	if m < n:
		return 0
	elif m < 2 * n:
		return 1
	elif m < 3 * n:
		return 0
	elif m < 4 * n:
		return -1

def do_comp(lst, idx):
	idx += 1
	out = 0
	for i in range(len(lst)):
		out += lst[i] * get_mult(idx, i)

	return int(str(out)[-1:])

def do_phase2(inp):
	s = sum(inp)
	out = []
	for i in range(len(inp)):
		out += [((s % 10) + 10) % 10]
		s -= inp[i]
	return out

part_1 = inp[:]

for i in range(100):
	part_1 = do_phase(part_1)

print("part 1:", "".join(map(str, part_1[:8])))

part_2 = inp[:]
offset = int("".join(map(str, part_2[:7])))
part_2 = part_2 * 10000
part_2 = part_2[offset:]

for i in range(100):
	part_2 = do_phase2(part_2)

print("part 2:", "".join(map(str, part_2[:8])))