For day 9, we’re trying to break a simple encryption scheme. Our input starts with a preamble of 25 numbers. From there, it continues with a series of additional numbers. Each number must be equal to the sum of any two of the previous 25 numbers. We’re trying to find the first number that doesn’t meet that rule.
Day 7 threw me for a loop. Basically what you have is a remake of the Matryoshka Dolls where you have a doll inside of a doll, only in this case it was bags within bags. We’re provided with a list of rules telling us which bags are within which bag. Ultimately we want to find how many bags can contain a “Shiny Gold Bag” within it.
So I didn’t write a year in review post at the end of 2019 but I would hazard to guess that if I had, it wouldn’t have included nearly anything that actually happened this year. To say that 2020 was a year that no one expected would be the understatement of the world.