Advent of Code solution: day 11

This is a solution for the 'Advent of Code' problem, day 11.
There is an array of octopuses, 10 by 10.
Each step, they increment in brightness until they reach a maximum and flash.
This causes them to increase surrounding octopuses in brightness by one, and reset themeselves.
The question asks how many flashes occur after 40 steps.
It then asks how many steps are required until all the octopuses flash at once.
This is a solution for the first part, and can simply be watched to show the answer for the second part as well.