aoc/2020/09/09.py

def read_file():
	with open("input.txt","r") as f:
		return list(map(int, f.read().split('\n')))

def has_summing_pair(target, numbers):
	for number in numbers:
		if target - number in numbers:
			return True
	return False

def part1(numbers):
	for i, number in enumerate(numbers):
		if i < 25:
			continue
		past_25_numbers = numbers[i-25:i]
		if not has_summing_pair(number, past_25_numbers):
			return number

def find_contiguous_sum(target, numbers):
	start = 0
	end = 0
	for i, _ in enumerate(numbers):
		start = i
		n = i
		s = target
		while True:
			s -= numbers[n]
			if s == 0:
				end = n
				break
			if s < 0:
				break
			n += 1
		if end:
			break

	return min(numbers[start:end]), max(numbers[start:end])	

def part2(numbers):
	target = part1(numbers)
	low, high = find_contiguous_sum(target, numbers)
	return low + high

def main():
	numbers = read_file()
	print(part1(numbers), part2(numbers))

if __name__ == "__main__":
	main()